


Koinophilia

by tiamatv



Series: Koinophilia [1]
Category: Supernatural
Genre: (Nothing about Eileen and Sam is explicit), Alpha Castiel (Supernatural), Alpha Eileen Leahy, Alpha/Beta/Omega Dynamics, Artist Castiel (Supernatural), Bottom Castiel/Top Dean Winchester, Bottoming from the Top, Castiel and Dean Winchester Need to Use Their Words, Established Castiel/Dean Winchester, Fireman Dean Winchester, Fluff and Smut, Gender Roles, M/M, Mating Cycles/In Heat, Non-Traditional Alpha/Beta/Omega Dynamics, Omega Dean Winchester, Omega Sam Winchester, Overstimulation, Top Castiel/Bottom Dean Winchester, Top/Bottom Versatile Castiel/Dean Winchester, Topping from the Bottom
Language: English
Status: Completed
Published: 2020-09-08
Updated: 2020-09-08
Packaged: 2021-03-06 20:00:34
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 3
Words: 22,014
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/26354605
Author URL: https://archiveofourown.org/users/tiamatv/pseuds/tiamatv
Summary: Everyone knew there was a strong correlation between an omega's physical build and their biologic cycle. Castiel didn't think that anyone would be surprised to learn that Sam, the six-foot-five, triathlon-running state prosecutor, went into heat just once a year.It should have made no sense at all that Dean, Castiel's mate, went into heat everytwo.And yet, somehow, it... did. It made perfect sense.So why was Dean being sosecretiveabout it?
Relationships: Castiel/Dean Winchester, Eileen Leahy/Sam Winchester
Series: Koinophilia [1]
Series URL: https://archiveofourown.org/series/2072823
Comments: 111
Kudos: 542
Collections: The Destiel Fan Survey Favs Collection





	1. Chapter 1

**Author's Note:**

  * For [ThePornFairy](https://archiveofourown.org/users/ThePornFairy/gifts).



> This was supposed to be a completely cracky little smut thing. 22K later, it's... no longer a cracky little smut thing. A lot of secondary/gender stuff decided to make an appearance. That said, it's still mostly fluff, domesticity, boys being exceptionally bad at communicating, and happy, enthusiastic smut.
> 
> No trigger warnings, but if you have very strong feelings about who you would prefer to be in control/topping/bottoming/etc, this may not be the story for you. (I think most of my stories may not be the story for you!) But if you liked [(Atypical) Love Story](https://archiveofourown.org/works/24668983), you will hopefully like this!
> 
> Thank you to [saltyravenclaw](https://archiveofourown.org/users/saltyravenclaw/pseuds/saltyravenclaw) for the look-over... picking this for one's first a/b/o fic to beta is quite an undertaking!

Castiel was seven years old when McMullin vs Lopez passed.

He didn’t understand the fuss yet then, not entirely—no-one would have expected him to, especially since, as it turned out, he was late to present. But Castiel understood that some of his siblings were excited—that Gabriel tried (failed) to grab him up and swing him around, then took off anyway; he knew that even Anna, who was nineteen, was babbling and laughing. He ran after them, and grabbed onto Gabriel’s leg when Gabe wouldn’t stop.

“What’s _happening?_ ” Castiel demanded. “Stop running around and tell me.”

Gabriel grinned at him. “The law just said I can be a policeman if I want, Cassie! Or open up a practical joke shop. Or whatever.”

Castiel considered this. “I think you should do the other thing,” he finally decided. “I don’t think you should _ever_ be a policeman, Gabe. Or anything like that.”

In all fairness, Gabe _had_ tried to explain in terms a seven-year-old would get. But even though Castiel had been quite precocious at that age, he couldn’t have begun to understand the importance of establishing secondary gender discrimination laws in the workplace.

(But to this day, as an adult, Castiel still remembered the joy leaving Gabriel’s face. He remembered the words his brother had used in response to _that_ innocent statement.)

At seven, he was so shocked by the stream of profanity—something about ‘indoctrination,’ something else about ‘fucking _Michael,’_ and more about knots than Castiel heard essentially until he started going through puberty himself—that he couldn’t even get the breath to complain that Gabe was cursing.

He _did_ remember that Gabe’s hand around his wrist hurt, and then it _really_ started to hurt, and then when he tugged and Gabe didn’t let go, he started getting a little scared.

“Hey! _Gabriel,_ ” Anna hollered, and grabbed Gabe’s shoulder. “You’re scaring him. Look, he doesn’t understand.” She kneeled in front of him, her hair falling around her face. Some of it was still floating a little from how excited she was, like a red halo. Castiel automatically reached out to poke it out of the way, and she gave him a little smile. “Cassie, why did you say that? About Gabe.”

Castiel refused to sniffle. He raised his chin, instead, and directed his words at his big brother—who was being _mean._ “You’re not very good at following rules,” he told Gabe, angry, straight-backed. “I don’t think you should be the one making other people follow them. But you like playing tricks a _lot_.”

Then Gabe didn’t look angry anymore, he looked _sorry,_ and the look that Anna was giving him over her shoulder was the one she gave people when they were in Big Trouble. Gabe went down on his knees in front of Castiel, too, and held him by both shoulders. “I’m sorry, Cassie. You’re right. You’re right about that.” Then he smiled, and there was something a little wet about it. Gabe shook him by the shoulders, gently. “You’re gonna be a really good little alpha someday.”

(Gabe and Anna both liked to claim that they’d been able to tell he’d present as an alpha even when he’d been little. Michael and Raphael, of course, both rolled their eyes at that.)

Gabe was certainly not a policeman now (though since Castiel’s favorite brother directed porn, and had been disowned by _both_ Raphael and Michael, he could only think that Gabe had _definitely_ taken Castiel’s young advice to heart). Raphael was a doctor, but so was Anna; Michael was attempting to make his name in politics, in Albany, and—a little to Castiel’s surprise—seemed to be succeeding.

Castiel, very gratefully, was none of the above.

So, given that it had been thirty years since the passing of that landmark law, he was standing in the Hilton Garden Inn Hotel Conference Center in downtown Manhattan, and most of Castiel’s coworkers _were_ omegas, Castiel couldn’t believe what he was hearing.

“—an alpha’s role is to be _strong_ for the cognitively gentle secondary. We’ve forced omegas to work and forgotten their original ventures—the home, the hearth. _Children._ It was all such a blessing, and what have we replaced it with?"

Castiel grimaced. He knew who it was before he even registered the crooning whine from across the stretch of the carpeted conference center hallway. He didn’t claim that his nose was markedly sensitive, but Adler always smelled a little to him like wet sheep. The tall, pompous windbag was holding court in an ill-fitting gray suit that even _Castiel_ knew was ugly.

“Omegas _want_ to be coddled and protected. Why should they have to fend for themselves?” Adler continued puffing his venom into the air even as Castiel stalked towards him. He normally had no interest in making a public scene, but enough was enough. “That’s why these new policies are undermining our _biologic duty_!”

'New?' Again— _thirty years!_ He _had_ overheard that Adler had been passed over for the head curator promotion…

“People have forgotten that we all have a biologic _destiny,_ and that of the omega is to breed, and that of the alpha is to nurture and support the weaker secondaries. _Especially_ those who are fortunate enough to be fertile,” Adler cooed, and turned, no doubt hearing Castiel’s footsteps. “It’s so _satisfying_ for everyone concerned—” His mouth curved in an oily smile. “Don’t you think so, Novak?”

“That an alpha’s role is to nurture and support their partner?” Castiel coolly repeated, raising his chin. “Well, of course. Everyone knows that.”

And when Adler’s shoulders went back with delighted surprise and the damned fool actually _brightened,_ watery blue eyes opening wide, Castiel continued, “I, personally, think that a good alpha partner would find it _wonderfully_ easy to nurture and support someone who can fly a space shuttle or shut down a courtroom with a perfect closing argument.” He smiled with just his lips—because smiling with teeth showing would have been _very_ impolite at this very moment. He could hear that the gravel in his voice was harsh enough to take off skin. “I believe that would be extremely satisfying. Don’t you?”

Zachariah Adler, cut off mid-rant in his hoary, antiquated, poisonous argument, gaped at Castiel from across the conference hall water dispenser with one thick-fingered hand suddenly crushing the little paper cone of water he’d been holding. Water was dripping into his cuffs and onto the convention center carpet.

Adler’s audience—a thin, weedy alpha with a weak chin and pomade in his hair, and a beta who looked too caught up in horrified car-crash fascination to actually protest the nonsense that Adler was spouting—took one sniff of Castiel and—wisely—melted away.

Castiel didn’t care. He didn’t look away. The whole ‘physiologic destiny’ argument was absurd to begin with, and it was twice as absurd coming from an alpha who was at an _archival arts seminar_.

Case in point: Castiel himself was likely a handspan shorter than Zachariah. Certainly less bulky. By those old biologic conventions, he _should_ be deferring to the other alpha. And yet he was very certain he was going to make Zachariah Adler regret that he had ever opened his mouth.

“But—” Zachariah snuffled, loudly. “How is anyone supposed to get anything done with _heat-scent_ in the air?”

The omega passing them by on her way to the next seminar room gave them _both_ a dirty look; Castiel couldn’t even blame her. He grimaced apologetically, and raised his chin enough to show the vulnerable curve of his throat to her.

What a stupid statement, though. The physiology of scent during heat was well-understood, and had been for quite some time. Multiple orgasms and an improved refractory period, yes—tendency towards distraction and violence, no. Did people still believe that an alpha could be incited to bad behavior by a whiff of someone’s fertility? Apparently so.

Castiel turned back to his fellow archivist; he could feel his blue eyes narrowing in a glare that was not friendly, and judging from the way Zachariah’s lips went white, Castiel’s scent was broadcasting his displeasure. Castiel wasn’t sure what anyone found menacing about the smell of leather and cinnamon—those were the main topnotes of his native scent when he wasn’t wearing cologne, and he rarely bothered—but Sam had assured him with a laugh that it was ‘really something, it’s really intimidating, Cas.’

(Sam, it should be noted, had not looked even _remotely_ intimidated as he’d said it.)

Castiel arched his eyebrows at Adler. “Are you telling me that an omega person—who has no control over the production of their scent—is somehow at fault for an alpha coworker not doing their _job_ properly? That seems contradictory. Weren’t you just talking about the duties inherent in being part of a strong, supportive secondary that isn’t hampered by…” Castiel tapped thoughtfully on his lower lip. The tip of one canine pricked at his fingertip. “What _is_ that adorably archaic expression you used? ‘Cognitive gentleness?’”

This time, Adler didn’t argue with him.

Or rather, he tried. He spread his stance, facing Castiel boxy and defiant, the line of his shoulders squared and his chin tucked in. He opened his mouth. The tip of his tongue moved just past his lips, like a worm.

Most of the time, Castiel did not know the right things to say to soothe, to comfort, to ease, to defuse. Dean laughed at his efforts at saying something romantic—which even Castiel knew came off ridiculous at times, and more often than not ended with both of them laughing. He didn’t use his secondary often—he didn’t even try to stare people down when they cut in front of him driving. He’d never once flashed teeth to his boss. Castiel was quiet, and most of the time, when he wasn’t angry, he wasn’t very good with words.

But Castiel _was_ dominant.

He didn’t raise or lower his chin. He didn’t tense at Zachariah Adler’s scent of fury and sour embarrassment on top of wet wool. He didn’t blink.

He _snarled_.

Adler dropped his chin to shield his neck, and didn’t say anything further.

That was probably the first wise thing Zachariah Adler had done in quite some time, Castiel thought, rather sourly, working his jaw to try to force his canines back in as he turned on his heel, leaving the human weed behind him shaking.

It was true, Castiel was not the sort of person who would throw a punch at a coworker at a conference unless physically provoked—he hadn’t gotten into an alpha brawl since a few months after he’d presented, and he hadn’t even had his first _growth spurt_ at the time.

However, he absolutely _was_ the kind of alpha who was going to be having a long talk with HR in the morning.

Even if Castiel _hadn’t_ considered Adler’s views repugnant—and he did—that sort of talk was inappropriate at a work conference to begin with! The other alpha wouldn’t have said anything that completely stupid about _women,_ so why—

Castiel grimaced as he stalked off. No, actually, he didn’t know that either. Adler _had_ been mouthing nonsense about fertility.

It was true that Castiel was a tall, broad-shouldered, and physically robust alpha. Even still, _he_ thought Adler was taking his own life in his hands voicing that kind of sentiment. Especially at a conference primarily attended by omegas.

(Imagining how Gabriel, even likely a half foot and more shorter than Adler, might decapitate the man at the knees, then eviscerate him tongue-first, and then finally proceed to set his car on fire, was a cheerful enough thought that Castiel’s canines finally retracted.)

Adler might have been unhappy at his position; should Castiel have felt pity for him for that? Adler might have even felt that his secondary entitled him to… what, precisely?

“Precisely nothing, that’s what,” Castiel muttered, and walked into the next conference room.

Hanna smiled at him from the next row of seats, and he shuffled over to make room for Castiel near the end of the aisle. Castiel took it, grateful, unbuttoning his suit jacket as he sat beside him.

Even though Castiel was already sweating a little in his suit and tie, Hanna always made him feel a little underdressed: his modesty collar was off-white today, the soft flat cloth wrapping his neck from just under his chin to where it bunched delicately just above his collarbones. It was lined with a row of tiny red buttons. Hanna always wore one, even though most people—even male omegas—rarely bothered outside of black tie occasions. 

He and Castiel had worked together more than once, sweating over boxes and crates in the dusty hive that was the back rooms of the American Museum of Natural History. (Why were the archival specimens never where they were supposed to be? The creatures had legs, but some were thousands of years old, and they certainly couldn't _walk_.) Even though it must have been sweltering, Hanna had never taken off his collar; Castiel had no idea what his scent was.

Hanna never made waves, but he also never compromised: he was _spectacularly_ organized, and he took things being out of place very personally.

Which was almost certainly why he—younger, newer, and omega—had been promoted over Adler.

“Congratulations,” Castiel murmured, before the talk started. “You deserved it.”

Hanna, the new curator of Land Invertebrates, smiled without looking at Castiel, quiet and serene. “Yes,” he agreed. “I did.”

Castiel didn’t even have time to chuckle before the very formal omega male he considered a friend—and now, technically his boss—was quizzing him about how work was going with the melittology project.

For the most part, Castiel was very content with his job sketching and painting tagged specimens too fragile or too old to be displayed, as one of the artists-in-residence at the American Museum of Natural History. At conferences, he still got sniffed periodically—sometimes politely, sometimes less so—but nonetheless: he had never _once_ in his life felt any urge to wrestle someone to the ground bare-handed or run into burning buildings to prove the presence of his knot.

Other people were much better suited to that sort of thing than he was. Regardless of whether or not they possessed a knot at all.

(Castiel’s opinion on that had nothing to do with just how _superb_ Dean looked in his turnout gear. Really.)

Not that Castiel had any complaints about how Dean looked now—loose-limbed and comfortable and very much in his own element at Chicory, Benny’s bar in Queens. Dean hadn’t dressed up to come out for the evening, but he didn’t need to. He wore open red flannel and a plain undershirt like he was going to shuck them at any moment, let his legs splay in loose jeans. Castiel smiled and studied the glorious lines of Dean’s bare throat, the roll of his Adam’s apple as he tipped his head back and drank his beer in an enthusiastic gulp.

Putting a modesty collar on Dean was a _sin_.

But Dean almost sprayed out his mouthful of beer and pecans when he heard.

“’ _Cognitively gentle?’_ ” he sputtered. “Holy shit, I can’t even remember the last time I heard that outside of like, fucking _Shakespeare_! Wow.” He wiped his mouth with the back of his hand. “Like, that’s bullshit that’s actually worthy of your air quotes, Cas.”

“Hey,” Castiel protested, mildly.

“Just sayin’.” Dean turned away from Castiel to elbow Sam in the side. “Hey, I thought there were policies about this kind of thing now. Can’t you do anything about that kind of crap? What’s that fancy degree of yours for anyway?”

“Really not that kind of lawyer,” Sam muttered into the mouth of his beer bottle. “Which you _know,_ jerk.”

“ _Bitch_ ,” Dean answered, a little too loudly, clearly delighted with the opportunity to be shocking.

A beta man walking behind them recoiled.

Benny, leaning on the bar in front of them, tried—and failed—to suppress a bark of laughter. “Hey, you keep a civil tongue in your head in my bar, chief,” he boomed, but he was grinning.

Castiel sighed and put a hand over his own face. Benny putting another beer down in front of Dean just _encouraged_ him.

He didn’t even have to open his eyes to hear Dean’s smile. “What? He’s my baby bro an’ I’m an omega too, comin’ from me, it ain’t an insult.”

Castiel cracked one eye open. Dean was grinning at all of them, lips just a little parted and the tip of his tongue resting delicately against the inside of his teeth, shoulders proudly back at the chaos he’d wrought. His whole expression broadcast delighted mischief.

God, that smile. Castiel didn’t know how anyone stayed annoyed at him. Castiel certainly couldn’t.

“Coming from _anyone_ it’s an insult,” Sam retorted, but he leaned forward and rested his elbows on the bar, looking past his brother at Castiel. “Are you going to report… what’s his name, Adler?”

Castiel nodded. “I’ve written up the incident and already have an appointment with HR tomorrow.” He wrinkled his nose in remembered distaste and started selecting the hazelnuts out of the small bowl in front of him, popping one into his mouth. “I’m going to bet it’s not the first offense.”

“Fuckin’ alphas, man,” Dean agreed. He passed over his own hazelnuts, already picked out of his bowl, and Castiel smiled his thanks. “If it’s not their dicks, it’s the brains at the base of ‘em.”

“ _Dean_.” This time, Sam looked genuinely annoyed—enough that his hair fluffed with it, just slightly. He gestured sharply with his chin between Castiel and Benny.

Benny snorted. “Don’t look at me, brother. He can say what he wants ‘bout me, he ain’t goin’ anywhere near my dick _or_ my brain.”

Sam choked.

Dean twisted and blinked, sheepish, and when he turned, it was to nudge an apologetic kiss against the curve of Castiel’s cheek. “Sorry. _Shit_. No offense, Cas. You’re the fuckin’ best. I just kinda forget you’re an alpha sometimes.”

Castiel supposed that someone else might have considered that an insult—especially since he and Dean _were_ mated _._ But, for one thing, Dean said that sort of thing at the firehouse all the time, and most of his colleagues were most definitely capital-A _alphas_. He chuckled and gently tilted his head just enough to let late afternoon scruff rasp against scruff. “You forget _everyone’s_ an alpha.”

Besides, he had every confidence in his ability to remind Dean of their respective secondaries, when he wanted to—and they both enjoyed it very much when that happened.

“Guess that’s true.” And Dean bent his head, sniffing ostentatiously at Castiel’s neck from close enough that Castiel laughed and shoved at his shoulder to dislodge him. Dean was so _rude!_ “Couldn’t miss how you smell, though, sweetheart, _mmmm_.” He sagged against Castiel’s shoulder and moaned, “Time to swoon, now, too cognitively gentle to _live_.”

Sam threw up one hand, almost upending his own half-empty bowl of nuts. “Oh my God, what is wrong with you? Every time I think you’re done, you make it worse. Now you’ve managed to insult _everyone_ ,” Sam told his older brother.

Castiel opened his mouth to note that Dean hadn’t insulted betas yet, but Sam’s point was, nonetheless, valid.

And Dean should not be encouraged in this.

Probably.

Castiel closed his mouth.

Dean winked up at him from his position with his head on Castiel’s shoulder, saucy, but straightened enough to turn a superior grin on his little brother. The same one that Castiel had had turned on him a _million times_ by his own older siblings. “It’s a gift,” he announced.

“Oh for crying out—hey. Wait. Speaking of terrible ‘gifts…’ actually…” Sam drummed his fingers on the bar countertop, thoughtfully, then turned his palm over, tapping his fingertips and visibly counting. “Hey, Dean, isn’t your time coming up really soon?”

Dean’s smile disappeared like Castiel had flipped the page on a drawing. He straightened away from Castiel’s side, leaving a long cold line where he’d been leaning. Castiel’s alpha grumbled.

Castiel rolled his eyes at it. Greedy for their mate, as always.

“ _Goddammit._ Don’t remind me,” Dean groaned. Sam slanted what looked like a markedly judgmental glare at his older brother. “C’mon, Sammy, don’t look at me like that, I put in my presentation papers at the firehouse last month. Bobby woulda killed me if I didn’t.” He grimaced. “Assholes are taking _bets_.”

Castiel blinked and folded his hands in his lap. Dean’s… Had it really been that long? “Do you mean…”

“Yeah,” Dean sighed and scrubbed a thumb against the shining surface of the countertop. “Probably gonna go into heat in the next couple of weeks.”

“ _Oh.”_ Castiel arched a startled, questioning eyebrow. Then, when Dean stayed silent, studying the dartboard on the wall like he could hit the bullseye with his gaze alone, he turned to Sam.

“The twenty-third,” Sam offered, helpfully, “if I’ve got my math right.”

Well, Sam always had his math right.

Castiel stared, then twisted to look at his mate. “Dean, that’s _next week!_ ”

Dean made a small, disgusted noise, but he didn’t meet Castiel’s eyes.

Castiel knew he should have been keeping track—probably—but it had been a very long time. That was just how Dean’s biology was; Castiel didn’t have any problem with that, they had not planned on children anytime soon. But at the same time…

No, Castiel didn’t agree with Zachariah’s point of view. _Any_ part of it. There _was,_ however, a correlation between certain aspects of secondary biology and the development of certain… physical characteristics, he supposed it could be said.

Dean was taller than most, Sam taller than almost _anyone_ , so he didn’t think that anyone would find it surprising that their heats were rare. Some omegas went into heat every month—Castiel felt _sorry_ for them—but those omegas who had rarer heats tended to be physically taller and broader once they completed their full growth. Anna had told Castiel that it had something to do with physical resources in adolescence not being consumed by the process.

Sam, the six-foot-five, triathlon-running state prosecutor, went into heat once a year. So it shouldn’t have made any sense that Dean went into heat every _two_.

And yet, somehow, with them, it… did. It seemed to make perfect sense.

Castiel sometimes thought that Dean had _stubborned_ his way into only having a heat every two years, just because it was inconvenient to have them any more often than that.

“Wait.” Sam looked between them, and his mouth sagged soft. The look he shot at Castiel was an apology given eyes. “Dean. You really didn’t _tell him?_ ”

“That’s none of your goddamned business, Sammy,” Dean answered, dark and low in his throat, the reverberation in it so close to an alpha growl that Benny looked over his shoulder from making a cocktail, frowning.

Castiel was frowning, too, but he swallowed the curl of unease. Or tried. They hadn’t been mated yet the last time Dean had gone into heat—they’d still been dating. They’d been dating for long enough that Castiel had been surprised, if not a little hurt, that Dean had chosen to sequester rather than ask Castiel to help him through it, but of course that had been his choice to make.

They were mated, now, and Dean still hadn’t told him. Hadn’t mentioned it at all.

“It’s alright. That’s short notice, though,” Castiel noted to Dean, quietly. He reached out and brushed the backs of his fingers down his mate’s side, his knuckles catching lightly on Dean’s belt loop. “At least I’m already meeting with HR tomorrow.”

The director might fuss a little about Castiel not putting in for partner-leave a month in advance, as he was supposed to, but she could hardly _refuse_ to let Castiel take the time off, not when he and Dean were formally mated. And he could get the most of his current projects closed off or sketched out by next week if he pushed—

Dean’s shoulders hunched inwards, his body language slamming shut.

“We’ll talk about it later, Cas,” Dean said, and that dismissive flick of his chin and the way he didn’t meet Castiel’s eyes settled cold in the pit of Castiel’s stomach. That was very much a _“we’re not going to talk about this, ever.”_ “Hey, I’m gonna hit the head, you wanna call for the check?”

He slid off his bar stool without waiting for a response from either of them, and went winding his way around the tables. Castiel watched him go, confused. His alpha ached and scrabbled at what was a very, _very_ obvious rejection, whining at Castiel to stretch his face out to rest it in the crook of Dean’s shoulder—scent his neck and bite hard on his mating mark.

“Dammit,” Sam groaned. “Cas, don’t take it personally,” he told Castiel, with a gentle pat of his shoulder, his arm long enough that he didn’t even have to lean over, even with the space of Dean’s empty stool between them. “But I didn’t realize he— _dammit._ ” Sam’s face squished in an expression that only Dean ever summoned out of him. “He’s… sensitive about it.”

“Yes. I gathered.” Castiel swallowed, and shook away his frustration along with the sympathy in Sam’s eyes. “But… I’d like to help.”

He _didn’t_ understand. _Everyone_ who presented alpha or omega went through the inconvenience of rut and heat. Castiel had envied betas more than once for it while he was sweating and panting, so on edge he wouldn’t have remembered to _eat_ if Dean hadn’t coaxed him into it.

Sam sighed, and his hand tightened. Cas’s alpha tried to raise his hackles—it didn’t want him to be touched right now by anyone _but_ his mate, not even an omega who smelled like family—but Castiel ignored it. “Yeah, I know, Cas, of course. ‘Cause you’re a good guy, and you’re a _great_ mate. But… you know how he is.”

He did know. He knew _exactly_ how Dean was.

So Castiel said nothing about it when they climbed into Dean’s beloved Baby. He chuckled weakly at Dean’s story about having to rescue some sort of foul-mouthed parrot from the roof of a house. He let them into their apartment, and smiled a little when Dean wrapped an arm around his waist from behind as soon as the door closed behind them, a big hand cradling the sharp jut of his hipbone. Castiel felt lips brushing in a soft caress against the back of his neck when Dean bent towards him, the whiffle of breath through his hair.

“Heya,” his mate said, warmly, and slotted his hips against Castiel’s rear.

Castiel reached backwards to run curved fingers up the side of Dean’s thigh, his nails rasping gently against denim. “I haven’t forgotten what we were talking about,” he warned, and extracted himself from the tight wrap of Dean’s arm—though not without running his hand appreciatively over the strong stretch of Dean’s forearm, from elbow to wrist.

He thought he was prepared for the expression that he was sure would be on Dean’s face when he turned around—the bright-edged smile that almost managed to make it all the way up to Dean’s eyes, the way he tilted his chin upwards in an attempt at charming guilelessness that Castiel would not have bought from him even _years_ ago.

Being prepared for it did not make it hurt any less.

“Aw, Cas. It’s no big deal.” Dean chuckled and shook his head. His grin was as bright and hot and destructive as the fires he put out. “You don’t have to take the time off for my heat. Seriously, I was just gonna get a hotel room and a dildo. Maybe a sheath if I’m really feelin’ it.” He tried to reach out for him again. “I’ll be okay.”

But Dean’s eyes had dulled to almost brown, not jade; the curve of his lips was pure art, but tension strained at the line of his jaw.

Yes, he would be fine; Castiel didn’t doubt that. But between Adler’s nonsense and the sinking feeling of hurt in his chest, being condescended to that way by _his mate_ bit sharply at Castiel’s otherwise rather imperturbable alpha nature.

An instant later found them both against the wall—Dean’s back to it, hard enough that his shoulders had thumped on the drywall, Castiel chest to chest with him and chin up, one hand pressed to the paint by Dean’s head.

“Ooh,” Dean crooned, looking entirely too pleased by this turn of events. He ducked his head to scent Castiel’s neck—deeply, lavishly, a loud inhale with lips parted. “So it’s like that? Okay, yeah.” Then both his hands went for Castiel’s back—one up his shirt and pressing calluses to his spine, one down the back of his slacks. “C’mere, Cas.”

Castiel knew he should resist. He knew he really _should_ —Dean was doing this at least partially to distract him as because he wanted it.

But he was helpless when Dean ducked his head and caught greedily at his lips, Dean’s hands already grappling him close. Castiel let himself be distracted.

God, he could get addicted to how responsive his mate always was, how _enthusiastic_.

No, that was fooling himself—Castiel _was_ addicted, completely. Dean was two inches taller than he was and Castiel was not small by any means, even within his secondary—but oh, every time Dean smiled at him like that, eyes shading low with golden lashes, expression going dark and warm and hungry, Castiel felt so _powerful._

Most of the time Castiel considered himself just the most fortunate of humans to have caught the attention of this phenomenal man across the floor of an otherwise completely unremarkable and, frankly, _boring_ museum fundraiser. He still didn’t know how it had happened.

“You kidding?” Dean laughed, when Castiel murmured his wonder into the warm infinity of that broad, star-freckled shoulder. “You were the hottest guy there, sweetheart—standin’ over in the corner with one eyebrow up, ninety percent dominance and ten percent blue eyes, and not a single fuck to give.”

“I had nothing I wanted to say to anyone,” Castiel protested.

Dean’s lips curved in a preposterous, delicious smirk. “Yeah, so basically, anyone who wanted to talk to you could just damned well come to you.”

(That wasn’t what it had been like _at all._ But that had been nearly four years ago, and Castiel had attended the same fundraiser every year, religiously, since. No, he didn’t care that Dean laughed at him for it.)

He had first seen Dean moving with purpose across the large ballroom room, absurdly handsome in a fitted black suit and the tiny, ridiculous red bow tie that all the firefighters in attendance were wearing. It wasn’t like anyone could have missed him, not a tall, tawny-haired alpha very much in his prime and on the prowl—broad shoulders and trim hips wrapped in black cloth, and long, long legs made for sauntering.

Castiel had no idea that this beautiful man was sauntering towards _him_ until he was already standing in front of Castiel—hip a little cocked in the most casual posture that Castiel had ever seen in formalwear, creases at the corners of his eyes Castiel wanted to rub with his thumbs, lips that he wanted to sketch, over and over.

(Dean was clean-shaven, that night. Castiel thought nothing could make him want to rub their faces together more. Until the next time, when he saw him with his cheeks and the line of his jaw sandy with scruff.)

Then the man shocked him further by smiling down at him and purring, low in his throat, “I’m Dean. Is it hot in here, or is it just you?”

Castiel blinked, very slowly, and peered down at himself, unwitting, embarrassed out of his own scattered thoughts. “I didn’t think it was particularly hot in here.” He couldn’t very well check his armpits. He checked his modesty buttons, but they were fastened. “Am I sweating?” It must have been both noticeable and _terrible_ if this stunning alpha, this _complete_ _stranger_ , would come over here and ask—

“What?” Dean gaped down at him, and then tossed back his head in a laugh that would have bared his throat if he hadn’t been wearing the high, closed collar of a formal occasion. “No—I mean—okay, okay, nevermind, that didn’t work.” He scratched the back of his head, and his grin—God, his grin softened; the floor dropped out from underneath Castiel’s feet, leaving him reeling. “Take two. You’re gorgeous. Can I, uh. Can I get you a drink?”

What?

Oh.

 _Oh_.

Castiel could feel his face going the same carmine as his number 19 Derwent colored pencil. But Castiel was also decidedly not alphasexual, and while he was so flattered—oh, God, _was_ he!—he had his mouth open to politely decline.

Then Castiel paused, because he didn’t normally watch the way other alphas moved across the floor either, trailing their smile like a sparkler. He hadn’t been able to wrestle his eyes off the covered line of that delicious, broad throat and his fingers were still twitching to draw the curves and lines of Dean’s hands, the angle of his elbow under the dark formal jacket. His knees were still weak, caught up in the vicinity of Dean’s smile—which was game, and just a little embarrassed, now, and so completely charming for it that Castiel wanted to bite on that lower lip.

Other alphas didn’t normally make him _blush_.

Well, what did _that_ mean?

In the confused, confusing interim, with no input whatsoever from his brain, Castiel’s mouth said, “Oh… yes, please,” instead.

His alpha purred and purred and _purred_ , rolling kittenish and delighted.

Dean undid his bowtie at the bar, leaving it dangling around his neck like a handle—Castiel tried not to stare, because staring at a stranger’s neck simply was _not polite_ , but the bright red tails draped around his covered throat like goalposts, or a picture frame. But it wasn’t until Dean released the first button of his own plain white modesty collar, complaining “How the hell aren’t you strangling in this thing?” that Castiel got the first whiff of bourbon and burnt sugar.

Maybe to someone else it would have been a relief to realize that he was not having a late-life sexuality crisis after all. Maybe to someone else that would have been important.

Castiel was self-aware enough to know, in retrospect: he’d followed Dean having no idea what his scent or his secondary were. It hadn’t _mattered_ what they were.

Castiel would never have approached Dean himself. He would never have smiled at a stranger across a crowded room with just a flash of tongue tucked between his teeth, confident in having their eyes unable to leave him. Dean didn’t worry about looking silly in a crooked bow-tie—Castiel’s eyes going wide as Dean reached across the thin air between them to touch the lopsided, plain black bow at the hollow of Castiel’s throat, a shockingly casual intimacy that left him holding his breath as Dean chuckled and delicately retied it for him with neat flicks of his blunt fingers.

None of that had anything to do with Castiel’s secondary or his dominance—Castiel was just not that sort of _person_.

He was grateful, every single day, that the man who would become his mate _was._

Dean was the kind of man who would take Castiel’s hand and raise it to his pulse at a formal occasion, slipping the tips of his fingers past the unbuttoned modesty collar as Castiel’s breath came faster, shocked and delighted despite himself. Dean was bold and shameless—he whispered “Y’know, I really like that you’re so damned polite—but if you’re plannin’ to be this polite when you knot me, _Cas,_ I’m gonna be disappointed,” as he slipped a phone number into Castiel’s pocket and sauntered off with a wink.

(Castiel had been unable to rise from his bar stool for the next ten minutes.)

Dean _was_ the kind of partner who would tease Castiel until his alpha reared up and snapped; Dean just grinned, unbothered, eyes darkening at the bite of Castiel’s dominance. It was a little to Castiel’s surprise and more than a little to his delight that Dean _loved_ those occasions when Castiel’s alpha snuck out to play—when Castiel grabbed him around the shoulders and flung him to their bed, one of Dean’s muscled arms tossed over his head and his broad chest on full glorious display.

Castiel was always _aware_ of his own strength—but Dean was _Dean,_ his size out of bed and _very_ much his match in it. Castiel had never had to worry about hurting or frightening him, not when Dean was more likely to grunt, “C’mon, harder,” or bite out, “God, yeah, _Cas_ ,” than ask for gentleness or reprieve. Dean moaned and cursed so _deliciously_ when Castiel held him down; when he moved and shoved while still buried inside him, tugging and pulling against each other even when knotted.

That was not to everyone’s taste—it was _so_ intense—but it was definitely to theirs.

Dean was so _distracting_ —Castiel’s insouciant, stubborn, cocky mate. He was always, always the gift that Castiel wasn’t sure he’d ever deserved. It would have been so _easy_ to let Dean have his way in this.

Perhaps that was why Castiel wouldn’t let him.

“Please,” he said, quietly, and nosed at the back of Dean’s neck, let his lips feather against the mating mark where Dean’s neck joined his shoulder. Dean was panting and limp in the curve of his body. Castiel splayed his fingers wider, held his mate close and plastered them together, covered him with his scent. “Dean, there’s no _world_ in which you would let me spend my rut alone.”

Castiel knew he wasn’t being fair to ask at a time like this—joined and spent, still knotted together, with Castiel’s fingertips straying down the streaks of come on Dean’s stomach. He didn’t care. Sometimes, when it came to Dean Winchester, dirty tactics were an absolute necessity.

Dean rubbed the bridge of his nose between thumb and forefinger and muttered, “ _Shit._ ”

~to be continued~


	2. Chapter 2

“He… agreed.” Sam’s tone was very flat.

Castiel squinted, and finally looked up from the tiny, glass-encased piece of amber, the fossilized remains of the stingless bee trapped within it. It had waited some eighty million years to be sketched. If Sam had taken the time to come to the museum, it could wait just a few minutes more. “Yes.”

“Like, he actually _agreed?_ ” Sam repeated, then clicked his tongue. “That’s… wow. Holy shit.”

Castiel could feel the darker, thicker hairs on the back of his neck rising with temper at the sound of his brother-in-law’s incredulity, and he frowned. “Yes?” he cocked his head to the side and set down his pencil. “Sam, not that it isn’t good to see you, but why are you _here?_ ”

“To make sure you didn’t feel bad about Dean being a dick, but I guess that’s out the window.” Sam leaned a hip against the drafting table, and undid the three buttons of his neat suit jacket so he could slouch to the side. Castiel sighed, a little enviously. He himself wore a suit for conferences and talks, of course, but he always looked _rumpled,_ he thought, rather than lean and elegant, the way Sam did. Or a walking sin, the way Dean did. “Look, Cas, uh. It’s really sweet that you wanna do this for Dean. But have you thought this through? You know no-one’s gonna think less of you if you tap out?”

Castiel’s canines pricked. Did Sam really think so little of him as his brother’s partner? Castiel knew that his alpha was fairly easygoing, but even _he_ let out a low, offended rumble at that.

Sam backed up a careful step, both hands raised and palms out, but he was smiling small, ruefully. “Well. Okay, then. Just… y’know. Maybe catch lunch with Eileen before, or something?” Sam shrugged a little sheepishly.

Castiel blinked and swallowed until his canines retracted fully again. “Oh.” Castiel liked Eileen a great deal, and he would not have been averse to lunch with her at all, but there had to be a reason that Sam was referring him to _his_ mate. “Sam, what aren’t you telling me?”

Sam scrubbed a hand through his hair, leaving it disarrayed. “I’d, uh. Dean… I’m gonna bet he didn’t…” Castiel’s brother-in-law wiped a hand over his face, muttering something behind his palm that sounded profane. “Of course he didn’t. Okay. I’d tell you to ask your sister, but… you’d probably have to tell her why you’re asking, wouldn’t you.”

Castiel blinked, and now he _was_ concerned. “ _Anna?_ ” His head tilted to the side. He was very sure that Anna—unlike Gabriel—wanted to hear _nothing_ about Castiel’s mated life, so that could only be because of her profession. “This is something… medical? Not just… Dean?”

“Oh, no. No, it’s not… nothing like that. It’s not abnormal. Any more than Dean’s abnormal.” Sam wrinkled his nose. “Though I guess he’s very abnormal.”

Castiel’s eyebrows rose.

“Actually, I take it back: all of this is on Dean, because if he’d _talk to you_ no-one else would have to,” Sam grumbled.

Castiel would never argue with _that._ That was, he suspected, always going to be a work in progress, with them. He tapped the base of pencil #66 (Chocolate) against the table, and waited, quietly.

“Look, I, uh.” Sam heaved a sigh, and both of his eyebrows wobbled. “Hell. He’s gonna kill me. Dean’s never had a partner who wanted to stay with him after his heat was done, alright? The last time he even shared a heat was with Cassie. So it’s… yeah. Since then, he’s been sticking it out alone.”

Castiel blinked and put down his pencil. He had to push the stiff archival board in front of him away so he didn’t crumple it. “Cassie? Cassie Robinson? The beta girl he almost mated with?”

Sam paused, and a few strands of his hair caught on his suit jacket as he cocked his head. He brushed them away from his face. “Huh. He told you about her.”

He had—though it had been casually enough that Castiel had realized how much the memory hurt, and he hadn’t pried too deeply. Castiel knew that she had broken Dean’s heart, but he hadn’t known _why_ , and finding _this_ out was making his back teeth ache—to say nothing of his chest.

“She left Dean after his _heat?_ ” Castiel demanded, appalled. What kind of person did that?!

Sam hesitated. “Um. During, actually.”

Castiel sucked in a shocked breath. This time, the growl that slipped out on the exhale was low even for Castiel’s own gravelly voice, harsh enough that it hurt a little coming out, and loud enough to _echo_ in his tiny office. His nails scraped against the surface of the drafting table. His mouth tasted sour.

“Easy,” Sam said, though Castiel rather thought that there was a touch of viciousness in Sam’s voice, too. “I mean, that’s all in the past, and you’re here for him now, and you know what? I’m glad you are. But I just… you know?”

Castiel nodded, once, jerkily, not trusting his voice yet.

“Please talk to Eileen, though? I bet she has some… uh. Tips.”

This was getting very suspicious. “Why do I need tips?”

“Long-latency omegas, like me—like Dean—we… I guess we get kind of… different during our time.” Sam hitched up an embarrassed smile. “Or at least _I_ get kind of grouchy, so, well…”

“Oh.” Castiel’s hackles settled, and he pressed a hand to the back of his neck to smooth the prickling hair back down. “Then yes. Thank you. I will reach out to her.” He bobbed his chin and looked up at the omega towering over him. “You’re a very good brother to him, Sam.”

“And you’re a better mate than my asshole brother deserves. So _you_ can tell Dean that he owes me a bottle of Woodford Reserve and this is absolutely my last good deed for the rest of _eternity,_ ” Sam pronounced, very firmly, and Castiel laughed.

*_*_*_*

Castiel did not, as a rule, care for lists, but he made one this time.

He filled the pantry with cereal and snacks, and the fridge with milk and eggs and bacon, aged cheddar and ground beef, plus a large par-cooked lasagna with enough meaty layers that he hoped Dean wouldn’t notice the vegetables Castiel had snuck in, too. He stowed the apple and cherry pies in the back of the freezer so they wouldn’t be consumed before Dean’s heat even started. He bought a case of Dean’s favorite electrolyte drink, and put a six pack of his mate’s favorite beer on the bottom shelf—Dean shouldn’t drink that when he was at the height of his heat, dehydration was a very real concern, but Castiel thought he might like a cold one once the worst of it had passed.

He hauled their thick winter comforter out of their storage locker and set it on the floor in front of the sofa—just in case—and added a picnic blanket on top of it. He took the pillows from their guest bedroom and put them in fresh pillowcases, arranging them along with their own on the mattress in piles. He lay down to test it, but it still wasn’t quite right: Castiel eyed the pillows critically and then went to the nearest department store to buy a few more, along with the fresh linens that were the only things that Dean had requested.

(He wasn’t sure _why_ Dean thought that they needed cheap new bedsheets, but Dean knew this process and his own body better than Castiel did. Perhaps it had something to do with the fresh crisp scent of new cloth? Oh, that was probably it.)

Castiel refused to buy cheap ones, however. He felt all the fabric samples against his wrist, and picked the softest.

In three different colors.

Castiel looked up from rearranging his new purchases in front of the sofa at the sound of their apartment door opening and closing, his mate’s tall silhouette filling the doorway from the kitchen into the living room. Dean stalled.

“Oh. Holy _crap_.” Dean looked around. “Cas, you are not kidding around.”

“Do you like it?” Castiel asked, shyly, his arms around a down-fill pillow. Why was Dean looking so wide-eyed, though?

“Yeah! I’ve, uh…” Dean scratched at the back of his neck, ducking his chin. “Never, uh, actually had anyone make a nest for me before? So, y’know. Wow.”

Castiel blinked. Wait. “ _Never?_ ”

Even with him having heats every two years, even with him having broken up with Cassie eight years ago, Dean was _thirty-six._ How was that even possible?

“Nah. I mean, s’been awhile since I shared a heat,” Dean dropped his hands and shoved both of them into his pockets, shrugging uncomfortably. “But I guess anyone who knew me well enough to take me through, probably figured I didn’t want one.”

Oh.

Castiel’s stomach tumbled, and the warm contentment he’d been feeling at arranging pillows and rumpling blankets until they weren’t flat on the bare floor vanished so quickly that cold goose pimples rose against the back of his arms.

Would he have realized that? Shouldn’t he have? He was Dean’s _mate_.

But he hadn’t been considering anything very sensibly, his instincts delighted by the task of making a soft warm space to keep his mate safe and comfortable when he was vulnerable. Castiel knew, _rationally_ , that Dean had gone for his injections this morning specifically so he wouldn’t be fertile during his heat. But his alpha simply didn’t understand or care about that.

He looked down at the pillow he was still holding, and then lowered it to the sofa and looked around at the—frankly, indulgent—cradle of soft things he’d built.

“I’m sorry. I’ll take it apart,” he began, his voice low and gruff. Of course Dean wasn’t the kind of person who would want a fluffy nest. What had he been thinking?

But before Castiel had time to grab up the edge of the comforter, Dean reeled him in against his front with an arm around his shoulders and pressed his lips to Castiel’s temple. “No, no! That ain’t what I’m saying. God! I’m really fucking this up. Don’t, Cas,” he murmured, his breath soft and hot against Castiel’s cheekbone. “I really do like it. It’s, I mean… it’s really _nice_. Nicer than anything I’d ever make for myself, that’s for sure. Don’t take it apart.”

There was nothing in his body that said he was lying. Castiel inhaled, eyes closed. Dean’s scent was always dark, especially for an omega—bourbon, salted caramel, the savory, umami edge almost like bacon—and so delicious that Castiel typically didn’t dare scent him in public. “Okay,” he said, softly, and his alpha rumbled its approval.

Dean nuzzled the arch of his hairline, his arms tightening, their bodies bumping together at knee and shoulder. Castiel blinked, but he hid his startled smile.

Dean was very loving, in his own way, but he could be quite… possessive. The first time Gabriel and Dean had met, no-one had been able to get a word in edgewise to let Castiel’s mate—boyfriend, at the time—know that the flirty, handsy omega was Castiel’s _brother_ before Dean had gone off on him in truly spectacular fashion. So Gabriel would probably always call Dean Jealous Asshole.

(Castiel had tried to tell Dean that Gabe truncating it to J.A. these days was a compliment, but Dean didn’t believe him. Since it was a lie, Castiel wouldn’t have believed it either.)

But all the same, his mate wasn’t normally _this_ casually affectionate.

Castiel reached up and tentatively ran his fingers through Dean’s hair, front to back, in the direction of the smooth line of Dean’s hair growth; Dean nearly _snuffled._ “There’s pie, too. But that’s for when you’re in heat.”

Dean groaned and pressed closer. “ _Damn_ , Cas. You’re so good to me, sweetheart.”

Castiel ran his thumb down Dean’s nape and rasped their cheeks together in a slow rub. Dean shivered and leaned in, but it wasn’t to taste or lick—he bent just enough to nestle his face in the crook of Castiel’s shoulder, and Castiel could feel his very tough, very dominant, firefighter partner _purring_.

Oh. Confused but pleased, Castiel kept his arms where they were.

This was unusual. But _very_ enjoyable.

Dean looked scent-drunk when he lifted his head a few moments later, and his smile was only a little sheepish. “Oh, hey, did you buy lube? M’sorry, I really should’ve mentioned.” He shook his head as if clearing it. “I don’t think we have much left, I can go get some on my way home from work tomorrow.”

Castiel blinked, very slowly, and his head tipped to the side. “Is that…” he began, hesitantly, wondering if there was a safe way to broach the topic, and then he realized that, well… no, there probably wasn’t. “Is that… oh, _Dean._ ” His stomach twisted. “Is… arousal an issue?”

That hadn’t even remotely occurred to him. They had some bottled lube for when they used their hands on each other, but other than that Dean had never needed much of anything to augment his own natural production. Castiel was cursing his own insensitivity now. There were some people for whom the reactions of heat were uncomfortable, their temperature so high that bringing it down was more an act of quenching than pleasure. Was _that_ why Dean preferred to spend his heats on his own?

Dean blinked at him, twice, then tossed back his head and _howled_ with laughter.

Castiel stared.

“Cas, sweetheart,” Dean managed, in between chuckles, “The lube ain’t for my sake… it’s for _yours_.”

_What?_

*_*_*_*

Castiel generally enjoyed the company of Sam’s mate very much, though as one of Manhattan’s most famous disability and secondary discrimination rights lawyers, he always felt bad about interrupting what little time she and Sam had together. With Eileen’s schedule, it had been quite awhile since they’d seen each other outside of holidays. Castiel was embarrassed to note that, in that time, he’d already managed to forget a few of the signs he’d picked up before—not that he would have known most (or any) of the signs for what they were currently discussing.

But Eileen looked very pleased to see him, greeting him at her office door with a hug and his name—her hand in a C, flicking off the crest of her shoulder.

“You still blush,” she giggled, looking delighted when she pulled back and patted his shoulder, then his cheek. “You have no-one to blame for that name but Dean.”

Yes, Castiel was aware of that, but having Dean call him ‘angel’ in front of other people enough that his _sister-in-law_ had begun to use it as part of Castiel’s ASL name was still embarrassing. He pulled back enough to make sure that she could see his face. “Thank you for meeting me,” he signed in pidgin, a little awkwardly, one-handed. He held up the bag of takeout. “Chinese?”

“Oh, you _are_ an angel!” she exclaimed, and ushered him in.

He supposed he _could_ have told her over email what he was coming to talk to her about. But when Castiel finally said it, after inquiring after her clients and her recent interview on the news, he certainly didn’t expect Eileen to put down her chopsticks and focus fully on him, leaning over her coffee table, her dark eyes intent. “Can you repeat that?”

Castiel would _not_ melt into her client chair in embarrassment. He sat up and folded his hands, instead. “Dean’s going into heat. Sam thought you might know something that can help?”

Eileen rolled her eyes, then stuffed a bright green stalk of kailan with oyster sauce into her mouth, chewing. “And the big shot prosecutor couldn’t tell you _himself_? That man.” But she said it so fondly that Castiel had to smile.

Castiel hoisted both of his shoulders, and took a piece of tapioca-wrapped shrimp har gow dumpling, finishing it off with a scoop of fried rice. “Well… I wouldn’t want to talk about my brother’s heat with his mate either,” he admitted. “Especially since _Dean_ won’t talk about it with me.”

Eileen put down her chopsticks again. “Is this the _first time_ you’re seeing Dean through his heat?”

The way everyone seemed to be stressing that was starting to make Castiel more concerned than he had any right to be. He straightened in the comfortably padded chair rather than shifting uncomfortably. “He only has one every two years. I’ve helped omega partners through their time before, I know how it’s done,” he protested, then frowned and shook his head, studying his tight knuckles. “Dean told me yesterday that _no-one_ has ever made him a nest. I couldn’t believe it.”

“Ah. Yeah, well. No-one had ever made Sam one either,” Eileen admitted, softly, and Castiel looked up sharply. She twirled her chopsticks through her rice, and took another bite. One side of her mouth curved up, bittersweet. “I caught him wiping his eyes when he pulled the covers back and found out I’d put silk sheets on the bed and bought him a body pillow that was big enough even for him. I thought he was going to throw himself into them going ‘Wheeee!’”

That visual might have made Castiel chuckle, but he found himself too angry to even smile—though he could _absolutely_ see why Sam had not wanted to talk about this himself. On another occasion he would have been very touched that his brother-in-law trusted him with this information.

“What is wrong with people?” Castiel muttered, his voice snarl-low, stabbing a dumpling hard enough that its contents burst out. “Why _wouldn’t_ they want something nice for their heats? Just because they’re so dominant? _I_ like a pillow nest, too.”

(It had only been a few decades since society had formally adopted the same terminology for certain scent and personality types in omegas as in alphas. However, when it came to Dean and Sam, Castiel was quite sure that no-one with any sense would _ever_ have used the omega-centric term ‘influential’ to describe them. No, not even fifty years ago, or a _century_ ago.)

“Well, that’s why we’re their mates, and those other people are _other people,_ ” Eileen told him, tiny and proud and _very_ alpha in that moment, putting out a whiff of bergamot and dark tea. It was very complimentary to the scent of their lunch. She considered him. “Have you heard the theory about why alphas nest?”

Castiel frowned, and tilted his head to the side. “Don’t you mean why _omegas_ nest?”

“They don’t, though, do they.” She waved a shred of braised beef brisket on the tip of her chopsticks. “I mean, of course everyone likes nice sheets and pillows, we’re all _people_. But you liked _making_ it, didn’t you? Choosing the fluffy things and filling the fridge. I bet you even put down blankets on the floor. Lay around in them for a bit to get your scent in them?”

“Well… of course.” Castiel blinked, surprised. “Isn’t that just what a good alpha does to prepare for their partner’s heat?”

She rolled her eyes. “That’s the party line, isn’t it?” Eileen leaned forward and her hands started flowing more and more quickly, the way they did when she was passionate—he’d seen her in interviews, and she was _brilliant_. “You must have heard about what happened at the museum a few years ago. When they had to redesign Human Origins.”

“Do you mean… I know some of the staff were talking about it.” He hadn’t paid that much attention—there was so _much_ to do in Biodiversity, the Human Origins exhibits were well out of his purview—but there had been that scandal… “ _Oh_. When they found out that the alpha and omega skeletons on display in Ancient Humans had been misidentified?”

“That’s the one,” Eileen’s hands said, and she nodded before she spoke. “Most ancient omegas were probably _bigger_ than their alpha partners. It would make sense if they went into heat less frequently. It’s only in modern times that omegas have had heats more often, and therefore gotten smaller in size, because…”

“More resources,” Castiel finished. “It’s safe to be fertile.” He wasn’t technically a scientist, but he’d worked in Biodiversity for long enough to know that.

She inclined her chin and tapped her hands together triumphantly, index finger and thumb extended. “We alphas were probably the ones who cared for the children and held the homestead. Cooked, made sure the fires didn’t go out. So—we all talk about alphas making nests for omegas, but historically? Those alphas were probably making those nests for _themselves._ Cave art suggests that omegas _defended_ the home and were the ones who went out to hunt. They carried the children to term _because_ they were physically stronger.”

So… like male and female spiders? Alright, even Castiel knew better than to make that comparison out loud—though he still wasn’t sure why so many people found spiders objectionable. He very much enjoyed drawing them.

Castiel leaned back in his chair and chewed thoughtfully on the end of his chopstick, looking absently down at the long line of his legs, stretched out in front of him. “That doesn’t exactly explain why alphas got _bigger,_ though.”

Eileen snorted, and wobbled “Silly” in front of her face. “Of course it does. Big body, lots of nutrition, fertile mate. ‘Pick me, healthy sperm!’”

Oh. So that was the sign for ‘sperm.’

Castiel didn’t want to admit that he blushed at that.

“But just look at us.” Eileen gestured to herself, one eloquent flick of both hands. “I’m an alpha female, but I’m _tiny._ My mate is three times my size and a state prosecutor, and if anyone ever called Sam ‘influential’ in my hearing I’d tear their throat out. But still I’m sure someone in his life _has_ called him that _._ And you! You’re built like an alpha, you smell like bottled _eau de dominance_ , and other alphas dip their chins when you’re mad. But you’re one of the gentlest, most artistic people I’ve ever met. Your mate boxes for fun and is about a _hundred_ times more likely to get into a fight than you are.”

Castiel couldn’t even deny that. That had _happened._

“Sometimes I look at how society still treats secondaries and gender, and it’s just… it’s absurd. Isn’t it?“ Eileen threw her hands up, then dropped them back to her lap with a raspy little growl. “It’s all made-up, none of that is actually _biology._ Is it that the male lion has a harem? Or is it that the lionesses do the hunting and share a pretty male lion between them because they don’t need anything more out of him than a bit of sex sometimes?” There was a rumble of alpha snarl in her voice, and she was flashing canine in a way she almost never did in the courtroom.

“So… you’re saying that Sam and Dean are throwback dinosaurs?” Castiel asked, carefully, holding his chin at neutral. “Because I don’t think I like them being the lionesses in this metaphor.”

Also, Castiel was _very_ sure they would not share with anyone else any more than either he or Eileen would want to be shared, but that was probably not what she meant.

She blinked, startled. But this time, Eileen laughed, and some of the intensity left her face; her canines retracted. She folded her hands primly back in front of her, setting them on her knees. “They’d like to be called dinosaurs, wouldn’t they.” She chuckled again, shaking her head. “Don’t tell Dean I said this, but I love the big idiot.”

Castiel was very sure that Dean knew. He smiled. “I do, too.”

She smiled back at him, sweetly, with just a bit of venom. “I know, Castiel. Everyone knows. A chihuahua with a cold would be able to smell it.”

“Why does everyone try to make me blush?” Castiel mumbled, running an exasperated hand through his hair. “It’s not funny.”

“No, but it is _very_ cute.” She grinned, but then shook her head. “Dean’s very independent. Right? He’s a firefighter, he’s big and brash and stupidly overprotective, raised his little brother to be proud of his secondary when that alpha turd father of theirs couldn’t stand that his boys were omegas. And you _love_ that about him, don’t you? We all do.” She didn’t wait for his answer. “He loves that you’re this very serious, very nerdy guy who worships the ground he walks on and doesn’t put up with his bullshit. And you love that he’s this cocky asshole who’s never thought he had to defer to you a single day in his life. None of that has anything to do with anyone’s secondary. Right?”

Of course not. But Castiel hesitated. “He’s actually been very, um. Cuddly, lately.”

“Awww. That’s adorable.”

“ _Eileen_ ,” he grumbled.

“But some things _are_ biology,” she finished, and since that was the last thing he had ever expected Eileen Leahy to tell him, Castiel bolted up straight in his chair and stared. She chuffed out a laugh at his reaction. “It’s true, though. Not who we like, not what we enjoy, not what we can do with our lives. But some things… can be, whether or not we’re happy about it.”

“I think—what Sam meant me to tell you—is, well… don’t get me wrong. I spend most of my working moments trying to tell people why society shouldn’t care about someone’s gender or their secondary. And I still think that’s true. _Society_ shouldn’t.” She grimaced. “But we also can’t and shouldn’t assume that everyone is immune to their own body all the time. Maybe not even Dean.”

She met Castiel’s shocked gaze, and shrugged. “I did a lot of research about this after Sam… well. Long-latency omegas have _very_ intense heats, Castiel. Intense enough to cause very dramatic personality changes in some of them. I think most of them try not to talk about it?”

Castiel nodded, very slowly. “Oh. Because of the subfertility nonsense?” Like the whole business about vaccines, he didn’t know how that urban myth persisted, despite years of evidence to the contrary. From an evolutionary biology standpoint, the idea of someone being unable to conceive just because they had fewer heats didn’t even make sense, other than as a method of discrimination: the reason why Dean had gone for injections rather than pills was that those who had fewer heats were comparatively _more_ fertile during them.

She pointed at his nose, then tapped her fists together. “You got it. So what would _you_ do if Dean wanted to kneel for you? Hug your legs? Kiss your feet?”

 _What?_ The noise in Castiel’s throat was shock embodied when he slammed back into the chair, almost a yip, higher than he’d realized his voice could still go.

“See?” Shame curled in his belly at the unimpressed expression on her face, the downward slant of both sides of her dark, expressive eyes. “Would it bother you if Dean’s clingy and needy and soft? If he wants to sit in your lap, if he wants you to pamper him and feed him from your hand in that nice nest you made? If he’s _submissive_? You’ve taken care of people who were like that in their heat, haven’t you?”

She arched a knowing eyebrow at Castiel’s wide eyes. He stammered, “But—” and trailed off.

Of course he knew there were omegas who liked that, especially in their heat. Castiel’s own _brother_ usually spent his heats eating ridiculous amounts of candy with his head resting happily between someone’s breasts, as he liked to brag. But _Dean?_

“But I bet it would bother _him_ to want that kind of thing _._ A lot.” She shook her head, slowly, and her mouth was tight. “So you’re going to have to work on that reaction you just had, Castiel.”

Castiel blew out a long, slow, embarrassed breath, and dropped his gaze.

Dean’s previous partner had _left_ him—mid-heat. He didn’t think that justified it—he didn’t think _anything_ justified it; that was a truly horrifying breach of trust—but a truly dramatic personality change would explain a _lot_.

“Is that what happens to Sam, though?” he asked, tentatively, looking back up after a long silence. “He just said he gets… grouchy.”

This time, Eileen blinked. Then she laughed, hard enough that it ended on a snort. “Oh, is _that_ what he calls it? No. Well…” she see-sawed her palms. “Sam’s _normally_ very careful and tender and sweet. Because he’s very conscious of his size and how strong he is. And he likes being taken care of anyway!” She laughed and fanned herself with a hand. “Then he _tackled_ me the first time I spent a heat with him. Gently!” she answered to Castiel’s expression of horror, and the way he wasn’t able to avoid looking her up and down to confirm she was still in one piece. “Sam was so worried what I’d think after. Stupid boy! But he really _is_ very different when it’s his time. Demanding.” Eileen shrugged. “He didn’t warn me before, either.”

Castiel blinked. “And was it… the first time, he was alright? After his heat wound down?”

Eileen snorted, and stabbed her chopsticks into her rice container. “Oh, you’re joking. He almost bolted before I sat on him.” She trailed off with a very eloquent gesture.

Castiel didn’t know that sign, but he could guess. If _Sam_ , of all people—by far the better communicator between the brothers, and _open_ in a way that Castiel thought that Dean had long forgotten how to be—had been horrified by his own personality shift during his time…

He nodded, slowly, and picked at a piece of dumpling wrapper. “You really think it’s possible that _Dean_ …?”

Castiel honestly _couldn’t_ imagine stereotypically porn-omega needy behavior out of his mate. It would never have crossed his mind. If it happened, he certainly wouldn’t love Dean any less for it…

But he could only imagine what Dean’s reaction would be once the heat started winding down.

Eileen’s lips quirked, a little sadly. “I think Sam knows him better than anyone, and Dean’s very obviously worried about something _?_ ”

Like being rejected for his heat. By someone who claimed they’d protect him at a time when he was vulnerable. By someone who should have _loved_ and _cared for_ him during it.

Castiel’s alpha, before Castiel could choke it down, growled aloud, so deep that his chest rattled. Castiel raised a hand to the base of his throat, grimacing and ducking his chin in apology. “Sorry. I’ve been… a little on edge.”

Eileen’s smile was kind, though, and more understanding than he’d expected, without so much of a flash of canine or a hint of answering aggression. “Castiel, you’re here talking about your mate’s heat with me because you want to do the right thing. I can take a little growling. If _you_ can go and work on not flinching if Dean’s heat makes him act in a way that you wouldn’t expect?”

“I can,” Castiel said, and it had the force of a vow to it. “Of course, I can.”

“Maybe enjoy it a little, even, if it happens? Big strong omega boy on his knees and begging for you?” She flashed teeth at him. “It’s not a bad thing, you know. Kind of fun.”

 _“Eileen!_ ” That statement had been very intentionally targeted to make Castiel red, he knew it. It was working.

Also, he had _not_ needed that visual of Sam, _not at all!_

“And just in case I’m wrong… you did buy lubricant, right?” Eileen added, smirking.

Why did people keep asking him that?

~to be continued~


	3. Chapter 3

As he opened the door of their apartment the next afternoon, the scent hit Castiel hard enough to send him reeling.

It was undeniably, unmistakably heat-scent. He’d been around omegas who were either going into or coming down from their heat, of course—his siblings, those he worked with, and those he’d been partnered with in the past. Very contrary to the nonsense Zachariah had been spouting, Castiel had always found the lingering echoes of heat-scent very pleasant—a neat slip underneath his senses, a hint of electricity keeping him awake and alert. The world seemed a little brighter, everything a little sweeter or more savory. Heat-scent was _lovely_.

But he’d never smelled anything even remotely like this before.

No, this _crashed_ into him, so thick with bourbon and caramel that Castiel involuntarily opened his mouth to it, half-drunk already. His keys jangled to the floor, followed by his satchel. His pencil box clanged on the tile and pencils spilled around his feet, but he barely noticed. He forgot how to walk. He forgot how to _speak_.

For a moment—just a moment—a tiny, snide voice inside his head chirped, “Well, Adler might have been right about _something_.”

Castiel staggered back, almost tripping on the colored pencils rolling underfoot, and it was the pressure of his body that slammed the door closed. Castiel barely registered the heavy strike of his own weight on his shoulder, momentarily dizzy with want as he clutched at the doorknob to keep his balance. He had to adjust where he’d gotten so hard in his work slacks, so suddenly, that even the thin cotton of underwear and Dockers felt unpleasant—too much, and too little.

The second thing that crashed into him was _Dean_.

Castiel could not in a million years have said how he ended up on his back without doing himself injury, but here he was: lying on the floor with the fly of his pants wrenched open with such violence that he felt the button pop and go skittering across the kitchen floor, his shirt only just barely yanked up and out of his waistband.

Dean was straddling him, and he was distracting enough when he was clothed. Naked, with his eyes wide and his cheeks already flushed red, hair a mess, he could scatter Castiel’s sanity like his pencils were scattered across the floor.

Castiel didn’t even have time to balance them together before his mate drew Castiel’s cock out from within his boxers—not gently, either. Castiel nearly choked at the sensation, Dean’s firm grip, but he still had enough mind left to lift up a hand to try and reach under, open Dean up—

Dean slapped his hand away with a growl and, instead, sank down onto him in one long stroke.

Castiel didn’t have the time to even be alarmed at the fact that he very clearly hadn’t had the chance to open Dean up at all, but Dean’s ass was wet and tight and _hot_ and spreading easily under the pressure without any spasm or hint of pain. His mate moaned loudly in obvious satisfaction, deep voice echoing through the kitchen. Castiel’s spine bowed off the floor with the shock of the unexpected.

Vaguely, he registered that the tile was quite hard under his back, but that was the last thought he had.

“Dean—” he gasped, ragged, trying to raise his head to regain some semblance of conscious thought—and lost his voice as Dean started to move on top of him with long, greedy strokes. The back of Castiel’s head thunked against the floor as he lost control of his muscles. He couldn’t have said that bothered him.

Castiel didn’t know where to put his hands. He didn’t remember _how_ to match him, Dean’s weight heavy atop him—a mile of skin—freckles effaced by his flush—parted, hungry lips. The scrape of Castiel’s zipper barely registered when his mate was riding on him in a bobbing, filthy grind that left Castiel’s pants and underwear sodden and clinging with Dean’s slick.

It was too much, too _sudden_ , and unbelievably good.

Castiel had barely opened his mouth to groan when Dean went still on top of him after no more than a dozen jerky strokes. His ass clenched in an exquisite, _torturous_ massage, and he painted the front of Castiel’s button-down with thick, hot stripes.

What? What, _already?_ He couldn’t—

“Mmm, hiya, Cas,” Dean purred, low and hoarse, licking his lips, while Castiel was still panting and squirming and unbelievably hard, wondering dizzily if this was some sort of insane, torturous sex dream. Did people have those before their partner went into heat? “Mmm- _mm_. I needed that. You feel so good, sweetheart. Ready to knock me up?”

Castiel couldn’t find an answer to that, wide-eyed and dazed, panting, but Dean didn’t seem to require one. Dean was already stroking himself with a rough hand, his cock not even softening fully before he was fully rigid again, pale precome beading at his slit and dripping onto Castiel’s…

…buttons?

Oh. Yes.

Castiel was still wearing all of his clothes. He was still wearing his _shoes_.

Dean rolled his hips before Castiel could actually process why that detail was important.

“Want you. Want your knot, this time,” Dean growled, and ground down, heavy and slippery and so perfect that Castiel, with a groan, wrestled himself partway into sitting and mouthed and bit at his mate’s bare, golden shoulder simply because he had to have a taste.

Dean was flushed and feverish, but he tasted of salt sweat and molasses, almost like smoky caramel. He laughed, low and knowing, at the feel of Castiel’s teeth. Blunt fingers striped through Castiel’s hair with a rough little tug.

When Castiel fell back heavily on his elbows, his stomach muscles cramping from how much he _wanted_ , his mate’s grin was triumphant—so joyful that Castiel felt his heart skip. He couldn’t have even said if it was with love or desire.

“Look at you, God, Cas. Mine, all mine,” Dean crooned, knees spread wide, thighs straining as he started to ride Castiel again with one hand braced behind him, hand gripping Castiel’s thigh like an anchor for them both. “Gimme your knot, pretty angel.”

In this position, Castiel could see just where they were joined, the warm shining slip of slick down his erection, the flush of Dean’s cock as it bobbed, still dripping generously. He reached out to touch, to run his fingertips down the bare flex of Dean’s abs as he moved. He could see the rise of his own swelling knot and—oh, God!—the quick rough pull as it disappeared into Dean’s body, in and out, the glide and pop of it like a jolt of sweetness and so _easy_ with how wet and open he was.

Until it wasn’t—until his knot caught against his mate’s rim. Even with Dean’s weight on him, Castiel’s hips shoved upwards, seeking. His hands found purpose, driving against Dean’s waist to hold him down, and Dean yowled as Castiel’s knot swelled to its full girth and locked them together.

Castiel had a split second of distant, horrified realization that he hadn’t so much as thought to see to his own partner’s pleasure _at all_ before the roll of Dean’s hips, and the sudden, intense _tug_ as Dean squirmed on his knot, yanked his orgasm from him in heavy pulses.

But Dean sounded _delighted_ as he gasped, “Oh, yeah—yeah, can feel that, fill me up, _fuck_!” and hunched over Castiel, one hand braced against Castiel’s shoulder hard enough to leave the crescent prints of nails on his skin, the other moving on his own red, dripping cock. He tensed, his back curling, and spilled again, thick and sticky, over Castiel’s shirt.

Castiel couldn’t have cared less about laundry in this moment, because Dean was clenching and rippling so intensely around his knot that it wrung a shout out of him, and he felt himself throb, spilling just a little more. But Dean still _wasn’t done_ , and Castiel thought his senses almost collapsed around him when Dean circled his hips in a victory lap that pulled Castiel’s knot hard against his rim. Castiel was soaked to the chest, but Dean’s hand was still moving on himself—still coming in drips with happy, greedy little whines.

Castiel was gasping and a little oversensitive by the time Dean slowed and released his own cock, licking his fingers clean with an absentness that sent a fresh shiver down Castiel’s back.

Dean still hadn’t gone soft. Oh, _God_.

But Dean’s expression was less wild, and his satisfied smile could have lit up the inside of his beloved Impala. “Fuck. You are so awesome, sweetheart,” he panted, eagerly, squeezing his eyes shut as he pressed a hand to his lower abdomen, the other resting on Castiel’s chest and crumpling the wet fabric of his dress shirt. He kneaded. “Knotting me up so good.”

Castiel was still dazed and hazy, and there was a pencil poking him in the side, so that was probably the only excuse for him mumbling, “Um… you’re… welcome?”

Dean blinked.

Castiel blinked back.

He didn’t know which of them started laughing first, but Dean was snickering so hard that he was snorting. Laughing while they were tied together in this position was strange and exquisite. The more Castiel tried to stop—because now he _was_ oversensitive, thoroughly—the more looking at Dean’s expression made them both start up again.

Dean was grinning again by the time they both petered off, his green eyes soft-lined at the corners when he looked up and down Castiel’s body. “Wow, you are a _mess,_ angel,” he announced, with a little chuckle.

Now, whose fault was that? “You don’t sound unhappy about it,” Castiel observed, slowly stroking Dean’s thigh with his palm. But when he studied his mate’s face, all of the hard, defensive push of the past week was gone from Dean’s expression. Dean’s happy smile down at him was a _balm._ Carefully, he asked, “How are you feeling?”

Dean’s grin was pure delight. “You kiddin’, Cas? I’m fuckin’ _fantastic_. You’re home, knotting me up. You made us a pretty nest to use. It’s already the best damned heat I’ve ever had.”

Dean’s excitement was contagious—even if it kicked Castiel a little behind the ribs to realize just how decisively Dean seemed to mean it. “Are you going to stay hard this whole time?” he asked, gently testing the curve of Dean’s erection with a finger trailing up its underside.

He'd known omegas who had rather… vigorous heat drives… but dear God. Nothing like this.

“Yeah. More or less. Have before,” Dean admitted, and shuddered on top of him as Castiel let his fingers close around the base of Dean’s cock. “Ain’t uncomfortable— _mm_.” Dean’s head tipped backwards as Castiel started rubbing his thumb back and forth, gently, along the ridge where the strong curve of Dean’s glans met his shaft.

“How long is your heat going to last?”

“Prob’ly three days,” Dean answered, but the last word trailed off into a hiss as Castiel started to stroke him—gently, the barest tease of pressure, until Dean’s hand closed around his and firmed his grip. “Yeah. Mm. Gonna come on you this time,” Dean muttered, wrestling with Castiel’s buttons with a remarkable lack of coordination. There was a moment when Castiel honestly thought Dean was going to just wrench him out of his damp shirt.

The tile was startling at Castiel’s back when they finally struggled him out of his button-down, but the cool of it felt good against his overheated skin. It took a little longer for his mate to lose control this time, arching over Castiel with both of his hands gripping and pawing at bare shoulders now. But the wet flutter of Dean around Castiel’s cock when he came, hot, onto Castiel’s chest and stomach was almost enough to renew his knot, which had only just _barely_ started to go down.

“You are _amazing_ ,” Castiel breathed, shaky and shuddering.

Dean smirked down at him, panting and proud. “Fuck _yeah,_ you know it.”

And _Castiel_ was the one whose knees were wobbly when, finally, Dean dismounted from him and helped him off the floor. Dean chuckled as he stabilized them both, Castiel reeling a little like he was drunk.

With his mate’s arms around him, Castiel stuck his head into the crook of Dean’s neck and inhaled sweet sweat and sweeter, darker burnt sugar, undertoned by just the slightest bite of dark grain alcohol.

Well, now he _felt_ drunk.

So. Eileen had been wrong. Completely.

Castiel could not for the life of him imagine why he should be bothered by this.

*_*_*_*

Castiel still wasn’t the least bit concerned by the second time—Dean bending to help pick up his pencils from where they’d been scattered across the floor had been a little too enticing. Dean came twice before Castiel’s knot even popped again—Castiel had always enjoyed that when they made love standing, they were the perfect height together for him to concentrate on Dean’s prostate.

(Even if it meant they were going to have to clean off the underside of the kitchen table.)

They _almost_ made it into the bedroom for the third time, but not quite: at least, they made it to the blanket nest in front of the sofa. Dean cooed happily as they rolled around in it, kissing sloppily.

Having Castiel’s mate on his knees on a cushion on the floor, his torso splayed forward over the sofa seat and the long line of his back tight with anticipation as Dean panted, “Yeah, God, yeah, just like that, _Cas_ ,” and rolled back at him like a tidal wave, was no hardship, either.

Castiel found, as he thrust in and bit Dean’s shoulder to hold him in place, and Dean groaned his appreciation of the pace he was setting and settled his hands on top of Castiel’s with a grip of nails, that he wasn’t feeling so drunk or wobbly after all.

When they were done—again—Dean chuckled, low and dark. “Mm. Damn, sweetheart.” He stretched forward—Castiel gasped as that pulled on his knot again—and fumbled a bottle of electrolyte drink that, apparently, had been left tucked between the couch cushions towards himself. “You are just planning to breed me up right, aren’t you, Cas?”

Castiel blinked, a little baffled. It wasn’t the breeding talk—that wasn’t a surprise; his mating instincts ran away with his tongue when he was in rut, too—but _he_ hadn’t put that drink into the sofa.

Dean was the one who rearranged them—pushing backwards until he was perched lightly, back to front, sitting in Castiel’s lap like holding himself up like that was effortless. His rear snugged against Castiel’s groin, knees splaying easily around his legs. Most of his weight wasn’t even on Castiel—Castiel admired the strong stretch of one of Dean’s thighs with the palm of his hand and rested his lips against his mate’s shoulder.

The coursing pulse of Dean’s throat moving was a beautiful agony to watch from close up, as he lifted his head and drained most of the plastic bottle in a few greedy gulps. But Castiel grimaced as Dean tried to pass the rest back to him. “No, thank you.” He didn’t really like those drinks, even though Dean did.

“Have just a little, sweetheart,” Dean coaxed, pressing the cold-condensed bottle towards him again. “Just a sip.”

Castiel wrinkled his nose, but he raised his head and took the few last awkward gulps of salt-sweet before settling down against Dean’s back again, tucking his chin over his mate’s shoulder with a contented sigh.

Why in the name of God hadn’t Dean wanted to share his heat? This was… incredible.

*_*_*_*

After the next time, Castiel barely had the forethought to snatch up the bottle of water from his bedside table—the bottle he _also_ hadn’t left there. Even though it was room temperature to his hands, it felt cold and sweet and so refreshing in his mouth. He emptied the container in deep hurried gulps, but a cool trickle of it escaped from the corner of his mouth and made its way down his jaw and neck.

Dean’s mouth fastened hungrily to the clear droplets before Castiel could even raise a hand to brush them away.

*_*_*_*

The shower felt _amazing_.

The fact that Dean refused to let him take it alone might have been part of that, but it did make it somewhat less effective in the process of getting clean.

*_*_*_*

By the next morning, jolted awake by Dean sitting down on his thighs, Castiel was starting to get a little… concerned.

But just a little. He understood, now, why Dean had wanted sheets that were probably going to have to be burned later.

Their whole room, their whole apartment, smelled so unbelievably, indelibly like _them—_ like sex, yes, but like _scent—_ a cross between a bakery and a fancy gentlemen’s club: cinnamon and brown sugar, leather and bourbon. Even just taking a deep breath was still enough to make Castiel’s whole body tremble with eager interest again.

Well, and if it was taking his cock a little longer to come back to attention, Dean certainly had… ways to convince it that it wanted to be involved.

Castiel probably would have had the mental space to be a little _more_ concerned if Dean hadn’t been so occupied with licking his own slick off Castiel’s half-swollen knot, growling playfully.

*_*_*_*

Castiel had, when he had first presented, suffered through some truly vicious ruts.

His parents, he remembered, had been extremely proud: the strength of one’s early ruts was supposed to be indicative of just how scent-dominant and physically robust an alpha one would grow to be, in much the same way as the duration of an omega’s latency between heats.

It had been an accurate prediction, in his case: for all that Castiel’s work was cerebral, his secondary biology meant that he was generally quite fit. Even with as strong as Dean was, keeping up with his mate in the bedroom had never been an issue.

By the evening of the second day, it was… getting to be an issue.

But Dean brought them dinner in bed, hurriedly reheated. They even managed to finish it and put the tray back on the floor before they were tasting pie filling off each others’ fingers. And mouths. And—

*_*_*_*

By the afternoon of the third day, it was _definitely_ an issue.

“ _Ow!_ ” Castiel yelped, and scooted himself up the bed until he hit the headboard. He pressed a hand down on the sharp ache on the inside of his thigh, and when he glanced down, there was definitely a print of teeth, already starting to fill rosy. “Dean, did you just _bite_ me?!”

Dean slithered up after him like he had fewer bones than he should have, gleaming and golden with his eyes dark and full. He licked his lips—then bent to nose aside Castiel’s hand, putting a kiss to the mark where he’d sunk his teeth. “You like being bitten,” Dean purred. “And I like biting you.”

Whether or not that was true—and Castiel had discovered over the past few days, a little to his surprise, that it _was—_ Castiel didn’t mistake that kiss on his thigh for tenderness.

That was _possession._

In the wake of _that_ statement _,_ Dean’s mouth coming open and teeth closing at the soft ridge down the center of Castiel’s sack was genuinely alarming—and if he hadn’t already been wholly backed up against the headboard Castiel would have tried to back away further.

But Dean was just… nibbling. Firmly. Firmly enough that the dangerous edge of it had Castiel sitting very, very still, half-propped up—he would have squirmed, but Dean’s _teeth_ were against some very sensitive flesh. But then Dean’s tongue darted out, playful and teasing, to soothe the tingling little marks he’d left behind on soft, wrinkled skin.

When Dean’s mouth skirted lower and he, surprisingly carefully, pulled one of Castiel’s balls towards his lips with gentle suction, Castiel shivered. When Dean opened wider to gently roll at its contours with the warm pressure of his mouth and the full width of his tongue, Castiel _groaned._

Well. Okay. That felt good. That felt _very_ good.

Castiel’s completely hapless penis tried to fill with renewed interest, seeming completely ignorant of the fact that Castiel was sore all over and covered with bite marks and hickeys, the dark thatch of curls around his cock had been perpetually matted for days with Dean’s slick no matter _how_ many showers he’d taken, and the base of his cock was visibly _bruised_ from how hard Dean had been clenching and tugging on his knot.

“I see you, pretty alpha,” Dean crooned, looking up the line of his body with his lips flushed plush and his tongue skirting the corner of his mouth. The sight of his beautiful mate lying there, shoulders braced between Castiel’s legs and looking up the line of his cock to meet Castiel’s eyes, had Castiel coming to a full stand again, his knot gently throbbing underneath his skin, and… ouch. That actually hurt a little. “I see you, you still wanna fill me up good, huh? Knot me up, keep me full? You can do that. We can do that.”

Castiel blinked, dazedly. Had Dean just called him ‘alpha?’ Dean never did that, any more than Castiel ever called him ‘omega.’

Castiel’s alpha pleaded _yes, yes, don’t you see he needs it?_

Castiel’s alpha, he thought, vaguely, was an _idiot._

That said, Dean was _so_ enticing, and… oh _God_ he had rolled over on their ruined sheets, and was presenting in front of him, knees spread and shoulders down and grinning at Castiel over his shoulder, so eager and so _certain,_ his jade eyes dark enough to get lost in. How was Castiel supposed to resist that?

He couldn’t. He _didn’t_.

The next time Castiel came, it wasn’t _quite_ painful, but it was very close—yanked from him by the clenching, rhythmic flutter of Dean’s muscles around him, leaving him spinning and breathless in a way that was not entirely comfortable. Castiel collapsed heavily on top of Dean’s back and tugged on his hip just enough to roll them to their sides and away from the newest wet spot, Dean humming and pleased, both of their hands slipping in the delicate film of sweat on Dean’s abs.

But Castiel’s knot only stayed up for a few minutes, and the noise that Dean made when Castiel slipped free of him was so disconsolate that Castiel’s alpha _whined_.

This time, Dean’s fingers meandered down his stomach; he tried to reach for Castiel again in a transparent attempt to coax another erection out of him—and yes, even with pheromones and the smell of sex so thick in the air and Dean looking at him so _hungrily_ it was going to be just an _attempt_ , Castiel simply could _not_ get hard again—

Dean’s thumb rubbed firmly at his frenulum; Dean sucked hard on his shoulder with a greedy hint of teeth.

Castiel’s body proved him wrong.

But the rasp of Dean’s calluses, even with the residual slick still drying tacky on Castiel’s cock, was still more sandpaper than slide. This time, Castiel flinched away and put a hand on Dean’s wrist.

“Dean… Dean,” he panted, “I think I need…” Dean’s fingers tightened, just slightly, and Castiel’s breath caught, his senses confused by wanting more of that pressure and less of the friction.

Dean nuzzled—and then bit his shoulder harder. Castiel’s whole body knew how to react to that, thrusting into the hand on him, pressing his shoulder up against his mate to feel his teeth—and yes, he was _definitely_ sore all over, because the pressure of Dean’s mouth, the sharp edge of it, felt wonderful… but even that jerky, sudden little twitch of his muscles to meet it left him unpleasantly dizzy.

“ _Dean_.” He encircled Dean’s wrist with his fingers and squeezed—not to pull him away, just a warning. Castiel breathed out a small sigh of relief when Dean’s hand loosened from around his cock again and Dean crawled up his body, sprawling at his side.

“What do you need, angel?” Dean purred, pressing small nibbly kisses up the line of his jaw that, under any other circumstance, would have made Castiel smile.

“A break, I think,” he confessed.

Dean blinked like he’d just gotten woken up from sleepwalking. He looked genuinely confused. He turned his head and glanced at where his hand was still resting—distinctly possessively—on Castiel’s erection. “Really? Oh.”

Castiel lifted his head to look tiredly down at where his penis was still trying to thicken up even further, valiantly, to Dean’s light touches, the back and forth stroke with the back of one finger teasing across the underside from base to tip. The blood beat in his temples, and he didn’t know if it was dehydration or lust or just sheer _exhaustion_ , but his whole body was sticky and his cock was chafed and sore.

Now he understood.

Dean was _not_ his opposite when he was in heat.

He was _exactly_ what he always was, only more so: dominant and bossy, aggressive and _reveling_ in it. All filters were off, and he was insatiable and magnificent and, well…

Just a little terrifying.

Castiel didn’t condone what Dean’s previous partners had done, but a tiny voice was asking him right now if perhaps their reaction had had something to do with _self-preservation_.

But Dean’s disappointment—the disappointment that he was now trying to hide, his eyes falling and his hand lifting away—was _heart-wrenching_. “Oh, fuck. Sorry,” he mumbled. “I—"

“I’m alright to keep going a little longer as long as you’re on top of me,” Castiel murmured, reaching up to cradle a hand against Dean’s cheek to keep him from turning away. Alright, he wasn’t _precisely_ sure that what he was saying was true, but what was the harm in trying?

How could he not at least offer, when he saw how Dean brightened hopefully again?

“I think I need some juice, though, first,” Castiel demurred, hesitantly. “And… maybe the lubricant?” Arousal definitely wasn’t an issue for Dean—that that question had ever come out of Castiel’s mouth seemed very distant and _extremely_ comical, now—but his natural slick simply _dried_ more quickly than synthetic lubricant did.

“Oh, _yeah_ ,” Dean crooned, happily. “Yeah, okay. I mean, I was hopin’… yeah. _Yeah._ You stay right here.”

Dean tumbled off the side of the bed, naked and _completely_ inexhaustible, trailing their mingled scents behind him as he skirted a pile of ruined bedding and sauntered through the bedroom door. He was whistling _,_ warm and tuneless.

Castiel would have tried to sneak a shower—alone and _not_ being sucked, stroked, bitten or sudsed—but in the balance between being temporarily and very briefly clean again or simply _lying still_ for a moment, it was hardly even a choice.

Castiel blinked hazily and closed his eyes, and he almost wasn’t able to bring his eyelids back up once they fell. He was very sure he’d never heard anyone so excited about _lubricant_ before, so why…?

But he was too exhausted to consider it. Thank God they’d left the lube bottle out in the living room at some point yesterday and had emptied the carton of orange juice they’d brought into the bedroom this morning, because even a momentary reprieve was a reprieve.

But Dean was sweet and solicitous when he came back, and Castiel found he _did_ have the energy to sit himself back up and stretch out his back, his hips. Dean reluctantly gave up the glass—Castiel refused to drink from it while Dean was holding it; he really wasn’t sure what Dean was up to with that, but he wasn’t an _invalid_ —but his mate leaned, warm and sweaty, against Castiel’s shoulder to drink his own, crunching on an ice cube. He had brought some crackers, too, and Castiel took one gratefully—though he did roll his eyes when Dean insisted on him eating _that_ from his hand.

Castiel knew what he was tempting when he licked the last crumb from Dean’s fingertips, but Dean’s delight and enthusiasm were as contagious as his lust, his deep, smoky scent. Castiel didn’t think he’d ever met or heard of anyone so _joyful_ in his heat. How could anyone not love that?

Of course, _Castiel_ hurt everywhere, his head had only stopped swimming for long enough for him to realize how dehydrated he must have been, and he wasn’t entirely sure _when_ his hips were going to recover from this. But the light snack had been restorative, and he was able to wobble his way out of bed unassisted and to the bathroom to brush his teeth, take care of business, a quick wipe-down.

“You’re okay?” Dean asked, looking up at him as Castiel came back. He sounded more lucid, less desperate, than he had in days—and, surprisingly, a little anxious. “You’re sure? I mean… pretty sure I’m on the way down. I’d be okay without.”

He didn’t know if Dean was asking if Castiel wanted this or if Castiel wanted _him_ , but it hardly mattered: the answer was the same either way.

Castiel smiled at him, and got back onto the bed, one achy leg at a time. “Yes, Dean, I’m very sure.”

“Thank fucking _God_ ,” his mate breathed.

In the next instant, lying flattened to the mattress with Dean’s mouth fastened onto his neck and his hands _everywhere,_ Castiel noted, a little ruefully, that he _should_ have expected Dean to pounce at that. But he laughed and reached up to link his hands behind Dean’s shoulders, kneading at the strong bands of muscle.

Dean did _not_ go straight for his target this time—which Castiel appreciated—and the rough calluses that had felt like too much on his cock were a pleasant rasp on his chest, down the arch of his ribs, and coming around to cradle behind his hip, shifting him around to Dean’s liking. He found himself smiling as Dean explored his bellybutton with his thumb—slower, now, less hurried. Less _desperate_.

“You really are the best, you know that, Cas?” Dean murmured, and the sincerity of that would have made Castiel want to try for once more even if he _hadn’t_ been relaxed and, surprisingly, feeling a bizarre sense of accomplished contentment. “The goddamned best.”

“You’re not going to say that when I’m making you do all the chores and I can’t _walk,_ ” Castiel chuckled softly and set his fingers gently into Dean’s hair, striping the tips of them down his hairline, and continuing behind Dean’s ears. Carefully, he skirted a fingertip down the nape of Dean’s neck—Dean’s was particularly sensitive, even for an omega, so he didn’t always enjoy being touched there.

Today, though, Dean arched his whole spine into the touch and purred, rumbling loudly enough that the vibration of it travelled through his sternum and trembled against Castiel’s shoulder. He was still purring when he started wriggling his way down Castiel’s body, and Castiel chuckled at the vibration of it—he didn’t stop petting.

The lubricant felt good when Dean poured a generous pool of it onto Castiel’s abdomen and a trickle onto his soft cock, rather than just wetting his fingers, but Castiel raised an eyebrow. “You _really_ want to make a mess of me, don’t you,” he observed, watching some of it purl down his groin creases.

Dean’s grin at him was so much of a promise that Castiel felt himself start to thicken up again. “Fuck, _yeah_ ,” he agreed. “Close your eyes, sweetheart.”

Dean’s hand was cool, and slippery enough with the lube that even Castiel’s soreness seemed trivial—pressure and glide, delicious, glassy smooth. It still took a little while before Castiel peeked down and saw that he was nearly fully erect again, but Dean didn’t seem to be trying to force the process, this time—just mouthing absently at Castiel’s ribs, twanging his tongue off them as he got Castiel’s cock and groin completely _sloppy_ with lube. The sharp edge seemed to be off his heat, and there was a patience to his mate’s touch that had been absent over the past few days.

It made him smile. Not that Castiel _hadn’t_ thoroughly enjoyed Dean wanting him so desperately. He would cherish the bite marks he was wearing all over.

Dean’s hand petted up and down his cock and continued down his scrotum, cupping with a gentle, soothing, slippery pressure. Castiel sighed contentedly and closed his eyes again, letting his thighs part as he went limp on the mattress. The wet stripes that Dean seemed to be drawing—little rippling horizontal lines like waves across his perineum—were a strange combination of soothing and arousing, and—

Then Castiel yelped and his eyes shot open as a cool, thick finger pressed further back, and ran a quick, insistent circle against his hole. Reflexively, he jerked away.

What—

Dean stopped. His eyes weren’t lucid, not quite, but they were _aware_. “Cas?” he asked.

Castiel let his back settle back down against the mattress. He shivered as Dean nudged the finger a little deeper, prodding and rubbing just barely at Castiel’s opening in a strange, aching tease. The closest Castiel had ever gotten to stimulation _there_ had been a finger at the stretch of his perineum, but this was not even _remotely_ the same sensation—more a tingle than a pressure. He knew exactly how big Dean’s hands were—so why did just one finger gently stroking back and forth in the crease between his buttocks feel so impossibly _huge?_

“You… what are you…” Castiel lost his train of thought again as Dean rested just the pad of his finger… right… _there_.

Dean was watching him, though. “Good?” he asked, hopefully.

“I’m… not sure,” Castiel admitted. “I didn’t… I didn’t know that you’d want…” Dean dipped his fingertip just barely _inside._ “ _Ah!_ ”

Castiel’s body clenched—no, _rippled_ around it. Oh. _God_. Oh, that felt _very_ strange…

But it wasn’t unpleasant. It wasn’t unpleasant at _all_.

“You didn’t think I’d want to be inside you, alpha?” and Castiel felt his own eyes go wide enough that he was sure he had whites showing all around. “Mark you up all over and make you smell like me for days? Fill you up so you know how good it is when you fill _me_?” Dean groaned, and Castiel twitched as teeth sank into the curve of his hip. Dean’s other hand, pressing underneath his belly button, held him in place. “God. Yeah. _Always_.”

Castiel bit his lip, breathing deeply into his own surprise. It wasn’t that he hadn’t thought about it—but he hadn’t thought about it _seriously_ , not ever. After all, he _was_ an alpha; he wasn’t alphasexual, either, and—

And.

And who, pray tell, cared about any of that?

This was _Dean_ on top of him, sweet-smelling, sweat-bright, big and beautiful and the love of Castiel’s entire existence, looking up at him hopefully.

Castiel nodded.

Dean’s finger, nudging deeper and deeper into a part of Castiel’s body that no-one had ever touched, felt unbearably intimate, and it was starting to feel quite _good_. Castiel licked his lips and let his legs spread further, gave Dean better access. He rocked his hips upwards into the touch, carefully.

Oh. Oh, that was _very_ nice.

Castiel did it again. This time, Dean’s finger slid deeply enough into him that his voice rumbled out of him, involuntary, in a small, eager sound. “ _Oh_ ,” he groaned.

Dean’s mouth almost sagged open—like even with those filthy, delicious words he’d poured onto Castiel’s skin, he hadn’t thought that Castiel would allow this. “Really?”

“Really,” Castiel confirmed. “Don’t stop.”

He’d thought he’d seen Dean happy in his heat—contented and pleased, if not quite sated. It didn’t compare to the delight he could see in Dean’s eyes now.

“Oh, fuck, _fuck._ ” He moaned the words into Castiel’s ribs, then bit down hard enough that the sharp edge of it ricocheted all across Castiel’s senses—pleasure and pain and stretch and _fill. “_ Cas, you are gonna _love_ this,” he crooned. “I bet you got one last good knot for me first. Then I’m gonna show you just how good you make _me_ feel.”

Oh, God.

Dean straddling him, facing away and rocking back and forth on his cock. Castiel watched himself disappear in and out of Dean’s body, swallowed up easily—so _easily,_ compared to how Castiel’s body tugged and squeezed and resisted around Dean’s fingers. His mate’s familiar wet heat wrapped around him was warm and sweet and almost dreamlike compared to the slow, achy burn and stretch as one of Dean’s fingers became two, and then three inside him.

The orgasm it pulled out of Castiel was startling, deeper and slower than he’d had in days—a pulsing through him, white-out and tender. It _was_ too much—his voice breaking on the noise he made, back aching as he tried to arch.

He registered, vaguely, that his knot was achingly full—his mind had been very willing, but he probably _should_ have stopped earlier. His thighs were dry, as well—for the first time, Dean hadn’t come—and some tiny part of him was vaguely embarrassed by that. They drifted, panting, tied—longer than they’d been since yesterday.

But then Dean was wriggling off him and coaxing him over onto his stomach.

Yes, they probably should have stopped earlier. But Castiel didn’t _want_ to stop.

“Oh, God. Pretty alpha. Just look at you—so soft and pink and tight for me. God, yes,” Dean moaned, running his hands up and down the sore muscles alongside Castiel’s spine and following them down. Castiel wasn’t quite sure he enjoyed feeling so _exposed_ when Dean spread his cheeks between his hands, but then two fingers—thumbs—were tucked between them, slipping and sliding across Castiel’s hole in a mess of lube. Both of them dipped into him, tugging and teasing where Castiel had gone soft, and now it felt nothing but good. “I’m gonna take such good care of you.”

 _My mate,_ Castiel thought, hazily, his mind wiped wet with that last orgasm. _My mate needs me. Wants me._ His alpha squirmed and rumbled in pleasure, completely eager, and Castiel arched into Dean’s hands, that warm, good touch, the firm palms on his rear.

“Yes,” Castiel agreed, mumbled sideways into a pillow that smelled like whiskey and burnt sugar, and shuddered at the first thick breach of Dean’s cock.

Dean held there, pressing just inside him in little rocking waves, and Castiel’s breath came in slow ebbs. Maybe it would have felt different—maybe it would have hurt more—if he hadn’t already been so sexed out and floating and relaxed. But he was, and the ache of it was _wonderful_ —the same concentrated edge as Dean’s teeth against his neck, as what he imagined partners enjoyed about being knotted. Even though it felt very strange, it felt strange the way Dean’s fingers had—warm and intimate and foreign, deliciously wrong-right, making space for _Dean_ within him where there had been none. Castiel’s skin was clammy and stung with goosebumps; he felt too hot and too cold, like it was too much and not quite enough, not quite—

Castiel hitched his hips experimentally into the stretch, and that _was_ a little too much. Too intense, the burn edged with pain. He gasped.

Dean stilled him with a hand on the small of his back. “Easy, Cas,” he hummed, rubbing his hand in small, soothing rings between his shoulder blades. He widened the circles until his thumbs were resting on the big straps of muscle to either side of Cas’s spine, pressing the spasm out of them. “You’re not used to this. Let me. We’ll go slow. I’ll make it so good for you.”

Maybe Dean was starting to get tired, too—he had to be, didn’t he? Or maybe he knew this was what Castiel needed, wanted in this moment—his mate, his omega, having him. “I know,” he murmured.

And he did know.

Dean took him in long, easy strokes. Every time he slid home, all the way—oh God, oh God—Castiel felt his knot throb, but deep: deeper than the scratch of his skin or the press of his own cock against sheets that would forever smell like them, like an echo of pleasure inside his pelvis.

Oh. That felt so _amazing_.

The urgency was gone. There didn’t seem to be any rush anymore. It was a leisurely, deliberate climb, the good hurt and tension of it building in delicate curlicues like shading, building upon layers of color and sensation until Castiel had to do something, he had to _move_. This time, when he nudged his hips backwards to meet Dean’s slow glide, Dean let out his breath in a tremulous sigh of “Yeah, yeah… Cas, take what you want.” In the quiet of their bedroom, Dean’s deep voice was hoarse as a prayer, the sound loud as a moan.

Castiel did moan, low and gritty, as Dean carefully shifted his angle and molded across Castiel’s back—heavy enough that Castiel had to spread his thighs to keep from toppling, but that just settled Dean that last final press into him, slotting him home so deeply that Castiel choked with it. Dean was still shaky behind him, barely balanced on his arms, nibbling his shoulder blade, craning his chin to lick Castiel’s mating mark.

They could barely move in this position, hugged as close as if they were knotted. It didn’t matter. They both rocked into it.

The deep pleasure of fullness and motion and _contact_ kept building, impossibly, until it was like a bass beat. Castiel realized that Dean was whimpering behind him, mouthing with increasing desperation against his skin, “Please, Cas— _please_ , alpha—”

It wasn’t lightning or fire or flood that swept Castiel’s senses out from under him. It was an earthquake—the tremor of it rocking him even though he had thought his muscles had no more to give, his buttocks and his pelvis and his hole moving in ripples. Dimly, he heard Dean moan and felt his hips stuttering in a few last rough thrusts into Castiel’s pliant body—thickening and wet inside him, that last, utterly _perfect_ hint of pressure.

The thin, nearly-clear drip of come that dribbled out of his cock was all Castiel had left in him before he collapsed under his mate.

*_*_*_*

Castiel hurt. All over.

The sheets underneath and pulled over him were warm and dry and smelling of citrus detergent—which, considering the way their sheets had smelled when he had last been conscious, that he’d been sleeping deeply enough that they’d been changed _around_ him. He was a little sticky, but there had clearly been an effort at wiping him clean—which he didn’t remember, either. The angle of the sun on the bed also suggested that it was afternoon.

He didn’t actually know which day’s afternoon, but no matter when it was, he was overwhelmingly grateful that he had taken the full week of partner-leave. Castiel wasn’t sure he could hold a _pencil_ right now, much less draw.

He cracked open one—disgustingly crusty—eyelid, then immediately squeezed it back closed.

It was too bright.

Castiel honestly considered rolling over to go back to sleep, except for two things: one, the thought of moving, much less rolling over, was repugnant; two, he knew exactly what had woken him up.

Dean didn’t pace quietly any more than he talked quietly, so the thump, thump, thump of his bare feet—even though he’d had the courtesy to have his screaming match with his little brother _outside_ their bedroom—was ricocheting through Castiel’s aching temples.

“ _Fuck_. Sammy, I thought… isn’t heat supposed to get _better_ with age? Goddammit, this was bad. It was really bad, I just… what do I even say to him? Yeah, I know I—sonofabitch, I _know_ that I should’ve, but—how the fuck was I supposed to—okay, _fuck you_ , _Sam_!”

In true Dean fashion, he also hadn’t closed the bedroom door.

“Dean,” Castiel growled, his eyes still closed. “I can hear you. Our neighbors probably can, too. You’re yelling. Please stop.”

The pacing stopped, abruptly.

Dean was fully clothed when he crept back into their bedroom, but it was in an outfit that Castiel only normally saw on evenings when he came home to find Dean under three blankets, watching Dirty Dancing and with his hair smelling like soot and smoke—Guns ‘n’ Roses band t-shirt that had since faded from black to an indeterminate grey, with the neckline so old and stretched out it sagged on one side, over a pair of Castiel’s looser sweatpants. He was limping. His expression was a strange combination of contrition and confident defiance, but the latter was very shaky around the edges.

“Hey, angel,” he mumbled. He had his phone clutched in one hand, and a pitcher of ice water in the other.

Castiel licked his dry lips, and his tongue almost adhered to them, his eyes fixing greedily on the carafe. He inched himself upwards until he was mostly upright against the headboard—which hurt exactly as much as he’d thought it would, but moving his limbs seemed to make every progressive motion hurt a little less. He finished off three full glasses, Dean silently refilling each one—and _not,_ Castiel noted, attempting to have him drink out of his hand—before either of them tried to talk again.

“I would kiss you,” Castiel ruefully studied his empty glass, and noted that even the drink wasn’t making him sound any less hoarse—even for him. “But I’m sure my breath is terrible.”

Dean blinked at him, finally meeting his eyes, as if… surprised? He didn’t even perch down on the edge of bed, the way he normally did on the occasions when he came in from a night out to find Castiel already tucked in but not yet asleep. There were times when Castiel _was_ most the way asleep that Dean sat down on his side anyway; he glided halfway out of dreams to the feel of a warm hand in his hair, or lips on the curve of his jaw, sometimes.

Castiel frowned and put down his glass on the bedside table, pleased to notice that his hand was shaking only a little and he didn’t have to clutch the glass.

(Though even frowning hurt a little. How was it possible that his _face_ hurt?)

Dean’s gaze dropped away again, and this time, Castiel’s eyes narrowed. “Sit down, please.” He tried on a small smile. Well, it hurt less than frowning, but Dean didn’t smile back. “You’re giving me a crick in my neck.”

Dean put down the pitcher and his phone and sat, still silent, the mattress dipping just barely underneath him. His body, the tilt of his shoulder, were turned part of the way towards Castiel, but his eyes weren’t jade and spring midnight anymore. His attention was gone, burrowing somewhere inside him—somewhere tired.

Castiel considered what he wanted to say, but ultimately, it really came down to just one thing.

“You should have told me,” he noted, in what he thought was a very reasonable tone.

Dean stiffened, and he stood in a rush of motion that made Castiel dizzy just thinking about it. But Castiel flung a hand out— _ouch_ —and grabbed him by the waistband of his sweatpants before he could leave.

“ _Dean_.” Castiel rarely let his alpha into his voice. He swallowed it down now.

“What the fuck was I supposed to say?” Dean answered, his back rigid but shoulders hunched, voice low and aching. “’Hey, sweetheart, wanna spend my heat with me? By the way, I turn into an aggressive sex-crazed freak.’”

Castiel turned his head just enough to raise both his eyebrows, unimpressed. He doubted he would have understood if Dean had said that, that was true—but it certainly would have been a start.

Dean blushed. “Oh, shut up,” he grumbled.

“I didn’t say anything.”

“You just had that whole damned conversation with just your eyebrows, Cas,” Dean shot back.

“I don’t like you calling yourself such things,” Castiel rumbled, and tugged until Dean backed warily towards him and sat, again, on the side of the bed.

Castiel wrestled himself the rest of the way into sitting without the headboard’s support and leaned his chest against his mate’s back instead, hooking his chin gently over Dean’s shoulder and winding both his arms around that tight, firm waist. He leaned in, giving Dean’s tense muscles his weight. Dean’s warmth wound through him, even through his shirt.

Normally that kind of gentle contact and pressure eased Dean even when he’d had a bad twenty-four at the station; not today. Castiel frowned, and nipped gently at the broad arc of Dean’s left shoulder, feathered his lips over the joint; Dean had an old scar stretching across it, like fingers where fire had touched him, but he liked being kissed there.

His mate shuddered. His hands slid upwards from where Castiel had seen them resting slack and limp on his thighs, and he gripped Castiel’s forearms hard enough that he thought Dean might shove them away.

Castiel clenched his jaw; Dean could _try_. He would probably succeed, but Castiel would not be making it easy for him.

But, unexpectedly, Dean clutched Castiel’s arms closer against his abdomen.

Very, very quietly, he said, “If you want to dissolve the mating, I… I get it, okay? I get it.”

Oh.

Dean had, after everything, still expected him to _leave_.

Castiel thought that he should be offended by that—but he couldn’t be. He couldn’t even be hurt—or, rather, he could, but not on his own behalf.

“If you’re feeling guilty about your total lack of communication—yes, you should,” Castiel told him, gently. The shoulders in front of him nearly bowed, Dean’s chin dropping to his chest, his nape a painfully vulnerable line. Castiel put a hand on Dean’s taut, clenched stomach, and rubbed. “But if you’re feeling badly for how you behaved or what you did—what _we_ did—while you were in heat… well, don’t. I’m not _upset_ , Dean,” Castiel murmured, and followed that up by nuzzling Dean’s neck, just over his mating mark.

“You’re… _not_?” Dean’s voice cracked in incredulity. “How the hell are you not—”

“My whole body hurts like the time we did that Habitat for Humanity project, and you’re definitely doing all the chores until the end of the week. But _no_ , I’m not upset.” He scented Dean, slowly, deliberately, on both sides of his throat. “You smell so good.” Even better than usual, his caramel undertones with a soft, almost toasted warmth to them, the bourbon mellow and smooth. “Did you enjoy yourself?”

“What the fuck does that matter?” Dean was still so tense and hunched in front of him, and Castiel’s alpha—which had really been feeling rather smug about the whole deal, to be honest—wasn’t exactly happy about that.

For once, Castiel listened to it.

He bit Dean. Hard—right at the nape.

Dean wasn’t particularly… omega in many things. Most things. But the way he went completely limp against Castiel’s chest with a gasp, sandy eyelashes fluttering, was _gorgeous_.

“What the hell, Cas, that wasn’t fair,” he muttered, but he was shivering with reaction. Castiel wrapped his arms further around him; Dean twisted a little, but it wasn’t to attempt to get free—he rested his head back on Castiel’s shoulder with the line of his throat a little more open—a little more trusting, like a gift.

“You weren’t listening to me,” Castiel gently tugged until Dean finally wriggled back with him, and they sprawled out together on the bed.

It really did feel so much better, being horizontal again. Castiel was, almost certainly, going to spend most of the rest of the evening asleep. He yawned and pressed his face against worn, silk-thin cotton, vaguely wishing Dean would take his shirt off. Skin would be pleasant.

“You’re really not mad.”

“Of course not,” Castiel huffed. He looked for the right words, but... were there right words? “Dean, you did _nothing_ wrong. And if you’d asked me beforehand, I _would_ have agreed to everything we did. You _did_ ask, and I agreed to it.”

Dean swallowed, audibly. “I wasn’t in my right mind, Cas.”

Castiel truly, _truly_ did not like the harsh rasp of self-recrimination in Dean’s voice. “Weren’t you?” Castiel raised his eyebrows, even knowing that his mate wasn’t looking at him and wouldn’t see him. “ _I_ was. Are you saying you didn’t want it? All of it, Dean? Any of it?”

Dean looked away.

Castiel twisted over far enough to kiss his chin, but Dean didn’t return the gesture. “You did. So what’s wrong with that? Some people want to… to, I don’t know, snuggle and laze around on silk sheets when they’re in heat. You just get…”

“Pushy and dominant as fuck?” Dean didn’t meet his eyes, lips turned in half a sneer.

“Dean, you have _always_ been ‘dominant as fuck.’ I thought you were an _alpha_ the first time I met you. I thought that all the way until you unbuttoned your modesty collar.” The memory still made Castiel smile a little. He imagined it always would.

Of all the things that could have made Dean meet his eyes, Castiel didn’t expect it to be that. “Wait. But… what? You _followed_ me. You’re not tri. Or alphasexual.” Dean looked down at himself like he was reminding himself of the lack of a knot under his sweatpants.

Castiel snorted out a soft laugh. “Yes, thanks, I’m very aware of that,” he answered, dryly. “So I can only conclude that I was stupidly attracted to you because of _you_.” He sighed and settled onto his back, folding his hands on his stomach and letting his eyes fall closed. “Are we really going to have to wait two years to do that again?”

This time, he knew Dean’s attention and his eyes were on him. “Wait, what _?_ You’d want—do _what_ again, now?”

“Any of it. All of it, Dean,” he answered, as clearly as he could enunciate. “I liked getting bitten by you. I liked that you _wanted_ me. I mean, I am grateful you don’t go into heat every month—I’d probably never be able to walk again.” Castiel reached down and rubbed a sore thigh, then glanced ruefully down at the impressive panoply of bite marks he’d acquired. Dean hadn’t broken skin, but it had been a close thing: actual teeth marks were visible in some of his bruises. “Or go out without long sleeves and pants.”

Dean was gaping at him.

Castiel let his tired eyes fall closed again, exasperated. “What in the world do you think is so terrible about my mate being so hot for me that he wants to pin me down and fuck me in every way imaginable? It’s how I feel about _you_.”

“It’s not the same,” Dean insisted.

“Because I’m an alpha? Because I’m male?” Castiel would have shrugged, but the motion didn’t seem worth the likely discomfort. “Because alpha males don’t submit to their omega partners?”

“Well, _yeah!_ ” Dean snorted, a little sour. “No-one bats an eyelash when I’m in turnout gear anymore, Cas. McMullin and Lopez and all, right? But God fuckin’ forbid I want to actually _use_ my cock.”

Castiel considered that, breathing in and out through parted lips. It was true that he’d never thought twice about Dean being a fireman, but it was also true that it hadn’t ever occurred to him that Dean might even want to… be inside him.

Until it had _vividly and very keenly_ occurred to him.

“By that logic, _I_ should be the one having some sort of a crisis about this. But I’m not,” he noted. “So why are _you_ upset? You’re the one who said that it was something you’ve always wanted.” He stretched just enough that his back popped, satisfyingly. “It’s not your fault I couldn’t keep up. But I don’t worry about breaking you. Why should you worry that about me?”

The bed lurched under him. Castiel cracked open an eye. Dean had rolled towards him, and his face was slack with incredulity, lips parted. He didn’t seem to have an answer.

But he didn’t try to bluff his way into saying that that had just been heat-talk again, either.

Castiel smiled and raised a hand to run his thumb over Dean’s bottom lip. “I really enjoyed myself. Couldn’t you tell?” Then he chuckled. “You know, I _was_ warned you might have some… mm… personality changes,” he admitted. “But I was thinking you might be more, well. Submissive. Not the opposite.”

“Oh. Oh, holy _shit_.” Dean flopped just a little forward, dislodging Castiel’s arm as he swung inside the circle of it, and his weak little chuckle against Castiel’s shoulder when his chin came to rest close enough for them to touch again was almost a better sound than him moaning. “Guess you were _really_ surprised, then.” He jerked his head upwards, eyes narrowing. “Wait, really? ‘Oh, please, please, alpha, knot me up, breed me!’” he squeaked in a comically high, thin wail before his voice lowered back to his deep, throaty roll. “Like… omega porn stuff? _Me?_ ”

Castiel snorted, but he let his forearm come to rest along Dean’s shoulder blades. His lips curved as he realized he had finger marks pressed into his biceps from one of the times Dean had been riding him. “You’re making fun, but you said that exact thing, just… in a _very_ different tone of voice.”

Dean’s blush started at the tips of his ears before it filled his cheeks.

Castiel stared. Everything they had done—everything they had spent the last three days doing—and that, _that_ was what made Dean blush?

“Oh, _shut up_ with the eyebrows already,” his mate muttered again, and dropped his flushed face to the mattress.

Castiel smiled and combed his fingers through his mate’s tawny hair. Dean grumbled, softly, and burrowed deeper against his shoulder. Castiel traced the path of freckles dancing across where the sun had kissed Dean’s collarbones, the backs of his shoulders. Then he lowered his head, slowly, and sucked a deep, deliberate mark into the side of Dean’s neck, pulling with lips and teeth and tongue—high enough that Dean would have to wear a modesty collar if he wanted to conceal it.

“ _Cas_ ,” Dean’s voice had slid lower again, and his muscles bunched pleasantly. “What’re you up to?”

“There,” he murmured, satisfied. “I can’t match all the ones you left on me, but you should at least have one to show off, shouldn’t you?”

Dean chuckled, softly, and nudged a knee up and over Castiel’s thighs, curling half on top of him. “Dude, you don’t need to neck bite me to brag, I am gonna be walking funny for a while.” Just as Castiel had managed to work up a hint of indignance about that— _Dean_ was sore?—Dean purred, a deep, throaty, silk rumble, “You fucked me so good, alpha.”

Castiel jolted.

Dean was definitely smirking at him now, just his eyes visible. “Huh. So you _do_ like that, too. Go figure.”

“Now you’re _really_ just trying to kill me,” Castiel grumbled.

“Mmh. Kill you with sexy.”

Castiel rolled his eyes. “Yes, you already tried that.”

Dean grunted, but he nuzzled in and pulled Castiel’s arm further around him. Castiel’s alpha vaguely considered that their nest was threadbare, now, and they should really get some pillows and shore it up. “M’gonna nap. I’ll make dinner, though. Want burgers?”

“You are the best mate imaginable,” Castiel sighed—and he meant it.

He’d thought for sure he’d end up falling back to sleep before Dean, but the next time Castiel glanced down, his mate’s beautiful face was slack and easy and peaceful, the tension softened out of it. The fresh mark on his neck was livid, beautiful. Castiel wondered how long Dean had been up and pacing and agonizing.

His phone beeped, softly, from his side of the bedside table, beside his glass. Ordinarily Castiel would have kept ignoring it, but that was the tone he reserved for family. He craned an arm over.

 _[Sam’s worried, Dean hung up on him,]_ Eileen had written. _[_ _What’s going on?]_

Castiel huffed out an exasperated sigh. Of course Dean had. _[_ _Nothing_ , _]_ he typed. His lips quirked. _[Though… you were wrong,]_ he added.

Small dots circled back and forth before Eileen replied, _[_ _About what?]_

 _[Most everything.]_ Castiel considered, then tapped out, _[_ * _Definitely* lionesses.]_

The dots started appearing almost before his second message whooshed onto the screen. _[_ _Oh, shit. Everything okay?]_

Castiel peered over the edge of the bed and snagged three of the scattered half-dozen pillows that had slid off the mattress, heaping them around them. Dean wriggled in his sleep and pulled one against his stomach, between them, tucking his knees around it. He was snoring, just a little.

Castiel smiled.

 _[Everything’s wonderful_ , _]_ he replied.

~fin~

**Author's Note:**

> Koinophilia: the evolutionary theory that animals prefer mates with a minimum of unusual, atypical or discordant features. (Obviously, in this case? A big fat _nope._ )
> 
> Thank you for reading! I hope you enjoyed it--or at least, that you weren't unpleasantly surprised!
> 
> This delightful challenge came from the [Profound Bond Discord Server](https://discord.gg/profoundbond). If you're so inclined to share in the madness, come join us!
> 
> Here was the prompt, by Alee: "Okay, where's all my cracky A/B/O with Alpha!Cas all "Ow, Dean, wait. My dick needs a rest." and Omega!Dean's like "Nooooo! breed me!! chomp"? Because I need some cracky A/B/O. Challenge those stereotypes! Alpha as dominant protector? Joke's on you, an alpha needs an omega to carry children, and to protect them and provide for them while the alpha cares for the home and the children. Size matters, because an alpha needs to be the last line of defence if his omega can't protect the den, and the alpha needs to be fertile and size/muscles = good nutrition and strong swimmers."
> 
> Also: apparently a lioness mates 20-40 times a day when in heat, and if her mate can't keep up with her, she bites his balls.
> 
> I really hope neither Cas nor Eileen knew that fact.


End file.
